The act of storing items that one would put in a fanny pack up the ass of ones self and/or in some cases the ass of another (sometimes willingly, sometimes not)
Yourself:
"$7.50 for a beer?! Fuck that! I'm fanny packing one in!"
Another:
Jon: "What do you mean you lost your car keys?"
Jamie: "Me and my girlfriend were fanny packing last night and I haven't seen 'em since."
The act of storing a cell phone with a google map app in your fanny pack while having sex. The app keeps track of speed, distance and duration for you.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi