In reference to The Matrix, like red pill or blue pill
Used to define someone who has suddenly become quite based
Man 1: I love colored lights and tomato soup
Man 2: Your cringe
1 year later
Man 1: I love committing hate crimes and also have multiple girlfriends
Man 2: Dude, you're basepilled
Coach: I need you to drink lots water. It'll make you pole vault better.
Athlete: Yes, of course. ABH.