its acutally just a word that you use to portray an emotion. it can mean pretty much anything, it all depends on the tone of voice you use with it. it is also commonly used to describe tarantulas.
Scrutinising a female booty, to excessive degrees, for the purpose of evaluating whether you wouldhave sex with her.
I've been bootanising that waitress for the last half hour. Let me tell you, I would crawl over hot coals and broken glass to hear her shit pipe fart through a walkie talkie. Her ass is that fine!