Aggressively hitting on women by force. Often times the "Bull Shark" will be extremely drunk/creepy, and grabbing girls that are not particularly interested in them. A patented "Bull Shark" move would be to grab the girl's face and forcibly make out with them.
Labeling somebody a Bull Shark works best while at the beach. Not only is there a "marine life" undertone in its name, but the beach is a prime location to hit on unsuspecting women, allowing you to creep from one bathing suit to the next.
Chris: Dude, look that creeper over there Bullsharking the fuck outta that girl.
Adam: Wow, she wants nothing to do with him. She keeps walking away from him, but he keeps buying her shots, asking to friend him on facebook.