When one surprises another with their gaped asshole (bent over) while screaming to draw attention to the act.
Fred: I just got out of the shower and Joe was waiting for me around the corner with a screaming asshole Steve: Damn Fred, how deep in did you see?
Fred: It was a deep screaming asshole for sure
This is in reference to a major asswhooping in either gaming or real life. The term "that asshole is whistling" is like saying they got so beat down that when the wind blows their asshole is whistling like a beer bottle.
You catch the fight last night on pay-per-view? Friend: yeah man, that ASSHOLE IS WHISTLING! He aint gonna shit right for a week!