Jeremy Shockey -- Trolls Warren Sapp ... Over Prostitution Arrest

Talk about kicking a man when he's down -- ex-NFL star Jeremy Shockey just threw some major salt in Warren Sapp's wound ... three years after Sapp called Shockey a "snitch" on TV.

Here's the backstory ... back in 2012, Sapp went on the NFL Network and said he had a "source" that told him Shockey was the "snitch" who ratted out the New Orleans Saints Bountygate scandal to the NFL.

Shockey denied the allegations -- and was furious that Sapp made the allegation.

Clearly, he's been holding a grudge and moments ago went on social media and posted the following note:

"Just heard from my SOURCE Warren Sapp charged with soliciting a prostitute! Damn so sad."

Yeah, clearly he's upset about it.