Literally: “under a plum tree or in a melon patch”.
Idiom
瓜田李下
a position that invitessuspicion; liable to lay oneself open to suspicion; be found in a suspicious position; in suspicious circumstances or surroundings
Etymology
Originates from a longer phrase 瓜田不納履,李下不正冠/瓜田不纳履,李下不正冠. It can be compared to the English-language idiom, “caught with one's hand in the cookie jar”.