舔狗 (licking dog) is harsh slang for someone who shamelessly flatters or chases a person who doesn't reciprocate. The famous quote 舔狗舔到最后一无所有 (a simp ends up with nothing) is widely shared as a warning.
usage
Can apply to romantic situations or to anyone excessively flattering a person in power. 舔 (to lick) alone is used as a verb: 你别舔了 (stop simping/bootlicking).
