It means you are agreeing with something

Tbh - to be honest. Is fucking overused and when ugly ass bitches post on their Instagram "comment for a tbh!" It means that they are gonna write some complete bullshit about how nice you when they don't even give two fucks.... And then the next day you find out that motherfucker ain't even following you back.

Tbh means to be honest. However, most people use it to flirt with other people or find someone to cheat with.

sixth graders on Instagram might say 'comment for a tbh' and other sixth graders do it because they like the attention. They are always fake and some times followed by a rate