So here's a list of things people's exes said to them that revealed they were lacking common sense:
Note: Some submissions come from this Reddit thread.
1. "I once told a guy I was dating he needed more humility, and he literally responded with 'Why would I want to be humiliated?'"
2. "My ex-husband didn't know you had to have a checking account, with money in it, and a credit or debit card to withdraw money from an ATM. He also pronounced ATM like 'Adam.'"
3. "She thought that rust was one of the chemical elements. You know like: oxygen, neon, silver, uranium, rust."
4. "I sometimes wonder what my grandfather thought the first time his wife told him that dogs attract lightning."
6. "I dated a manager of the produce section of the grocery store. He didn’t know what crudités was, thought my portobello mushrooms weren’t cooked through because they were white on the inside, and wouldn’t eat any yellow cheese because he thought it was made with carrots. Also, he thought strawberries were sour."
7. "I dated a girl in high school, and she was generally very bright. We were at the mall one day, looking at one of those big maps of the mall directory. She asked me how the map knew where we were standing. Dumbfounded, I asked her to clarify. She pointed at the point at the star on the map that said 'You are here,' and asked how the map knew. I explained that the map was where we were standing, and we are reading it. After 10 minutes of trying to explain, she still didn't get it."
8. "My best friend had a boyfriend one time that refused to drink water because it said it was unhealthy and caused cancer. His solution was that he only drank soda or diet soda. All day every day."
9. "My ex broke several coffee cups trying to reheat her coffee on the electric stovetop. We had a microwave. Why she tried to use the stove, I don’t know. Why she continued to try it after the first one broke, I don’t know. She had a master's degree. I finally bought her a plug-in coffee cup warmer, and she loved it."
10. "He got dicey fajitas from Chili's, got food poisoning, and then ate the leftovers."
11. "He thought cutting the umbilical cord determined penis length. He legit thought it was the doctor's fault for cutting it 'too short' if a man had a smaller penis and didn't realize the cord was what caused people to have belly buttons. He didn't think girls had an umbilical cord to cut at all when they were born."
12. "My ex would only drink whole milk because when he saw 2% milk, he thought, What’s the other 98%? He thought he was a genius."
13. "She was a 40-something woman and asked 'Is duck an animal?' Everyone in the room got real quiet and just looked at each other."
14. "I dumped a guy because he didn't know what color red and yellow make when mixed together. It was a question on Are You Smarter Than a 5th Grader? When I asked him to just take a wild guess, he goes 'I don't know, purple?' That's when I knew we were done."
15. "I had to teach my ex how to locate a book in a library. We were both college graduates."
16. "My now-husband, when we were first dating, told me that he believed that all plants could be classified as either a fruit or a vegetable. After we were married, he told me he thought platypuses were the size of golden retrievers."
17. "My ex asked me, 'What kind of animal is Mickey Mouse?' I just kept saying back, 'Say that again…slower.'"
18. "When I found out my ex didn't know what order the months go in. When I asked him to learn, he got mad, said no, and that it wasn't something he was interested in."
19. "After homecoming in high school, we went for pizza. She wanted to try a vegetarian diet, and as we were selecting toppings, she asked me, 'Is there meat in mushrooms?'"
20. "I once briefly dated a dude who thought sweetened coffee had zero calories because 'the sugar has dissolved, so it’s not there.'”
21. "My ex once sent a ridiculous text, and I made a comment about how many double negatives he used. He called me a dummy and said it wasn’t math, and it was cute how I thought that double negatives had anything to do with language."
22. "She said playing basketball makes you taller. Her proof was all the tall people playing basketball."
23. "When we were first married, my ex wanted to cook dinner by himself so I gave him an easy recipe to follow and made sure he had all of the ingredients. He had me come look at it because he said it looked too dry. For one of the ingredients, he’d read 'two and a half cups' as 'two half cups.'"
24. "We were talking about dinosaurs and he was shocked to hear they were real. Then, he proceeded to ask me if they really breathed fire. He thought dinosaurs and dragons were the same thing."
25. "When he missed his daily medication, he threw it out instead of just saving it for the next day."
26. "When he said he’d make pancakes and then put the dry powder directly in the hot pan."
27. "My wife would bring stuff home that said 'refrigerate after opening,' open it, and put it in the refrigerator."
29. "She didn't know that yogurt and pudding were not the same thing. She thought it was like how the British call fries 'chips.' She had been eating pudding and granola for breakfast for months and congratulating herself for being so healthy."
30. "She didn’t understand that you actually have to pay what you spent on credit cards. Like the credit amount she had was supposed to be her monthly limit that just resets each month."
31. "My ex asked me, 'Where does the sun go at night?' I was dumbfounded. She was in her early 20s at the time."
33. "She walked into a computer lab on campus and simply picked up a computer and walked home with it. She was living with me at the time, so I get home to find a very familiar-looking computer sitting on the kitchen table. She literally thought the computers were free for students. It took a bit of explaining to convince her that she stole the computer. I made her return the computer to the lab that night; she left it at the doorstep."
35. "I once asked my ex to start boiling the potatoes for dinner about 20 minutes before I got home so that they would be close to ready for me to mash up as the side for dinner. I got home right as he put them in the water. He had to call his dad to ask how to boil potatoes."
36. And lastly, "I introduced him to my stepsister. He said, 'Weird. You guys look nothing alike.'”
Submissions have been edited for length and/or clarity.