It could be that the kid is sick and covering the mouth to prevent germs from spreading. Or perhaps they saw something they weren't supposed to and are trying to stay silent.
The cartoon kid might be covering the mouth because they're laughing too hard or trying to hold back a scream. It's hard to say for sure without more context.
Maybe the kid is trying to hide a secret or keep quiet about something.
It could be popular because it triggers people's curiosity. They might wonder what the kid is trying to hide or why they're covering their mouth. Also, the visual might be artistically appealing.
Maybe the kid is shy or has something secret to keep.
Maybe it's trying to hide a smile or keep a secret.
There could be various reasons. Maybe she saw something unexpected and is covering her mouth to keep quiet. Or it could be part of her character's mannerism to show shyness or surprise.
Maybe he's trying to hide a laugh or a secret.
Maybe he's trying to hide something or stop himself from saying something.
Maybe she's sad about something that happened and doesn't want to show it too much.
It could symbolize keeping quiet or hiding something. Maybe it represents secrecy or trying to stop oneself from speaking.
Maybe it's because it looks cute and catches people's attention easily.
Maybe the kid is about to speak or shout. It could be part of an expression of surprise or excitement.