You know what?
I love that Sokka and Bolin are always clowning around. I know people think being the comedic relief character is a bad thing but do you know how much care and effort goes into making other people laugh?
Like putting aside your own hurts and fears and baggage to cheer up others is hard. Bolin and Sokka aren't as stupid as they act, they just play it up.
Making people laugh and smile in times of stress is hard because you have to shove all of your own stress aside and joke it up and smile and pretend its all going to be okay even when you don't feel it will.
Sometimes you've just got to let that built up energy out and it might as well come out as laughter.
Like pretending everything is fine and giving your humor to others? That's learned behavior.
No doubt Bolin and Sokka picked it up to make Mako and Katara feel better or less stressed. After all a joking and happy sibling is a safe and cared for one. Then they just extended it as their friend groups grew.
And don't get me started on when they slip up and drop the charade. Sometimes people are more concerned the comedy stopped over the character's emotions and that can lead to people overlooking their more emotion heavy moments for their funny ones.
Like comic relief characters are vital man, because who else will make you laugh when you really just want to cry?