吃瓜群众 Chī guā qúnzhòng

“guā (melon)” here refers to gossip, news or personal
information of someone else. It corresponds to the “tea”
in the similar English expression”spill the tea”. “Chī guā
(to eat melon)” decribes the state of the onlookers.

吃瓜群众

Chī guā qúnzhòng:

onlookers who are interested in the spectacle but don’t have anything knowledgeable to say about it.