Can't figure out line of dialogue

Every time I see this scene, it drives me nuts: When Chris first finds the two beachbums and makes his initial deal, he goes to their van and gives them a sample, then sells them some of the drugs.

As Chris is leaving, the guy at the door puts Chris' sunglasses back on, says "We'll see you real soon." Chris replies, "depends on my boss, he killed a guy once."

As Chris gets out of the van, the guy at the door turns to his buddy and mouths something, some additional line of dialogue. I have yet to figure out what he's saying. I don't know if he's just repeating the line, making fun of the "killed a guy" statement, or something else related to Chris, or what. Anyone know?