stop putting your hands on your mouth

idk if this started on tik tok but y'all need to stop putting your hand on your mouth whenever you want to react to something like is this a trend?? i stopped using tik tok when it required for an account so idk but it comes on insta, like why do you do that when you laugh or something, is it some kind of expression?? I did it at some point only when I'm shocked but after seeing others & doing it more I stopped myself so I just want to ask...why?