ウケる
Ukeru
うける
Originally 受ける (ukeru) means "to be well-received" or "to be popular," but in slang it means "that is funny" or "that is hilarious." The go-to reaction is ウケるんだけど！ (ukeru n dakedo!) — basically "I am dying!" or "that is so funny!" Spread from 1990s ギャル語 (gal culture slang) and is still going strong today. Can be used genuinely or sarcastically.
Examples
え、何それウケるんだけど！
Wait, what?! That is hilarious!
Reacting to a friend telling a funny story
何もわかってなくてウケる
They have no clue what is going on — that is so funny
Making fun of someone who does not understand the situation
お母さんのLINEの使い方がウケる
The way my mom uses LINE is so funny.
自分のミスなのにウケてしまった
It was my own mistake but I could not help laughing at it.