It's a scientific fact that it's impossible to dislike Jennifer Aniston. Rich Fury / Getty Images I'm a science expert, so I know it's true. I once dissected a frog in high school! She's Rachel Green! America's sweetheart! Hydrated Smart Water queen! Tap to play or pause GIF Tap to play or pause GIF Tap to play or pause GIF Tap to play or pause GIF Warner Brothers And, honestly, all of Hollywood seems to love her. Case in point: They all showed up to her 50th birthday party over the weekend. View this photo on Instagram instagram.com But the most telling sign of all is that even her exes are still huge Fanistons. Brad Pitt showed up to her party, and her recent ex, Justin Theroux, shared this sweet tribute to her: View this photo on Instagram instagram.com The photo itself not only shows off Jen's sense of humor, but it also reminds us all that she has the best arms in showbiz. "Fiercely loving. Fiercely kind...and fiercely funny." Kevin Winter / Getty Images We stan mature, supportive exes!