The Brief: An indirect is a message, post, or tweet that calls out a specific person or event without giving details.

DEEP DIVE
Indirects is a term for messages, tweets, and posts that call out or refer to an individual or an event without disclosing specific details. Indirects are synonymous with subtweets.
According to Urban Dictionary, the term “indirect” dates back to March 2018. The entry shares an example where it is used as a verb. “Did you see Zoey’s finsta post?” “Yeah omg she totally indirected you wtf.”
u think ur safe? i check my indirects
— Official Among Us Struggle Tweets (@amongustruggles) September 16, 2020
if ur joke somehow offends someone, apologise thoroughly and not make fun of them for it or even tweet indirects for everyone else to see. this platform is a safeplace for everyone, let it stay that way.
— ً (@MALF0YZ) September 15, 2020