Used to convey a feeling of disgust or sickness. It is most commonly used as a sound effect for someone throwing up. Variations include 'BUHgaggle' which adds a powerful emphasis to your disgust and 'blaggly' which describes something disgusting.
Dude 1: "Last night while I was fucking that girl from the club I couldn't see my dick because her stomach rolls were covering it."
Dude 2: "Oh my god! Blaggle!"
Dude 1: "Whatever man she's so hot."
Dude 2: "I've never seen anything more blaggly in my life dude, sorry."