No filter

When someone describes themselves as "having no filter" what they really mean is "I'm a massive cunt but you can't get angry at me because I find myself funny"
They also get angry when you call them out for being a cunt and often get really upset when you are a cunt to them.

Person A: "hahaha that guy got hit by a car that's pretty funny"
Person B: "wtf is wrong with you?"
Person A: "I just have no filter haha I'm so random like that"