Here are some of the top answers:
Disclaimer: These stories have not been verified. The users are supposedly speaking from their own experiences.
Some entries have been edited for length/clarity.
1. "I waited on Kate Winslet and her friends. They were the loveliest people. We had a pub dog, and Kate sat with the dog on her lap and chatted to me for ages about what I was studying at uni and the history of the pub/village. They had burgers and a few bottles of wine. She tipped nearly 50% (!) and asked for the soup recipe.
"She's everything you think she'd be and more."
2. "An ex of mine waited on Stanley Tucci and his wife Felicity Blunt a few years ago, and they were super charming and tipped really well."
3. "I waited on Matthew McConaughey and his family twice. He left around a 25% tip. He was very polite and reminded his children to say 'please and thank you to this nice lady.'"
4. "When Dancing with the Stars siblings Julianne and Derek Hough were on tour years ago, they stopped at a restaurant where my niece was working. She was eight months pregnant and waitressing mind you, and they left a $0 tip!
"Talk about low class!"
5. "I served Vanessa Hudgens ice cream at a baseball park, and she didn’t tip anything. I barely got a greeting when she came to my stand.
"I understand she was trying to keep herself hidden, but she could’ve at least said hello."
6. "A few years ago, I worked in a restaurant at an airport and had the pleasure of seeing a few famous people. My favorite one was Robin Roberts from Good Morning America! Her meal was maybe $15, and she left a $20 tip!!!
"She was awesome and a pleasure to serve!"
7. "I waited on Blake Shelton once a few years back when I worked in a bar/music venue in Nashville. I think he was there to support a friend performing. I had no clue at the time who he was (I didn't listen to country), and I didn't know until the guy performing told me after. Blake was super polite, very southern, and tipped me $50 on a $16 check.
"He had a burger, fries, and a Bud Light, in case anyone's wondering."
8. "I worked at a hotel as a housekeeper back in the very early 2000s. The movie The Hunted was being filmed in my hometown. The hotel restaurant (a higher tiered seafood restaurant) hosted the main actors in the movie (Tommy Lee Jones, Benicio del Toro, etc.) several times, and according to a few of my friends who worked there, they either didn’t tip at all, or left only a few bucks on the table."
9. "In 2014, I got a tip for room service. $150 from Emma Thompson. Took me five minutes, and she was so nice.
"10/10, would serve again."
10. "I work at a restaurant in Senoia owned by Norman Reedus and [The Walking Dead director] Greg Nicotero. Norman and Greg are great tippers, and they're always very sweet. I’ve served Greg a few times, and he never leaves less than $50. Sometimes, he'll leave $1,000 for all of us servers to split. Cooper Andrews (Jerry from The Walking Dead) came in one afternoon with his super cute wife, and they were just delightful. He left me $50 on a $50 tab."
11. "I used to work in a pub in Manchester during United's '90s-'00s heyday. I met many of the United footballers in there, including Paul Scholes, Cristiano Ronaldo (though only once), and Roy Keane. All great guys. Tipping isn't as forced a thing as it is in the USA, but they bought a round of drinks for everyone in the pub and left a £10 each for all the bar staff.
12. "I waited on Belinda Carlisle from the Go-Go's when I was a room service butler at the Ritz Carlton back in the mid '80s. I was very nice to her and her bandmates, and they scrapped up a bunch of change and gave me pennies as a tip."
13. "Matt Dillon was in town filming a movie. He came to our restaurant, but we had already been closed 15 minutes. I was the manager, so I let him in, made his food so the kitchen staff didn’t have to stop their end-of-the-day duties, and comped his food. I explained I had already closed out the registers. The young woman working the front and I got to chat with him while we went about our closing duties. He finished his food, thanked us repeatedly, and then left. When she went to clean his table, he left her $150!
"If I had gone ahead and charged him, his food and drink would have been about $20, and a good tip would've been $4-5. This was the early ‘90s, so it was pre-internet, pre-social media. So, he did that out of the goodness of his heart. He got no PR out of it. Really great, humble guy."
14. "Chi McBride [from Boston Public] tipped just north of 30%, and he was one of the most genuinely nice people I ever waited on."
15. "My cousin used to work at this little coffee shop out in rural southern Ontario, and one day, Dan Aykroyd came in. For whatever reason, it was cash only, and he threw a fit because he didn't have cash. The poor cashier who didn't recognize him got flustered and helped him pay for it out of her tips, and he didn't even thank her for it.
"I know this story is very secondhand, but it's always stuck with me. I get that it's frustrating, but just, wow."