Red Hood: Lost Days #5
Jason gets cornered by the Ivgene clan while trying to sabotage some bombs, and his “plan B” is to throw up on the guys shoes to convince them that he is just a kid who was hired to help the guy who made the bombs. They start to believe him, and Jay goes on to beat the shit out of them.
....But this begs the question: has Jason always been able to vomit on command? If so, that’s pretty cool and really disgusting.