It means hahahahaha. In Spanish the J sounds like an H in English. You can laugh like this on posts to confuse people and/or make fun of Mexicans.
Meg: I'm going to shit so hard from these greasy ass tacos.
by Kenfo April 13, 2016
Jajajajajaja is hahahha in Spanish it just that they pronounce j's as h's like jalapeño (Hal- a- peen- yo)
Person 1:*tells joke in Spanish*
by TheDefinitionTeller April 12, 2016