The act of fucking someone from behind, getting a mate to take over without the person noticing, then runningoutside and waving at them to scare the fuck outta them.
Inspired by the rastawhitey cop in Leon, who says 'watch your bombakhan mouth', so it can either be used as a substitute for fucking or as a postive swear word.
Shut your bombakhan mouth = shut your fucking mouth.
That was bombakhan man = that was ace man.