I first realized that I was bisexual when I allowed my younger brother to insert his erect penis into my rectum and fuck me until he came in me and pumped his seed deep into my willing body where I wanted it in there and that it belonged in there.
to gem002 :This goes for anal sex in general. Throw in the fact that the orifice is traditionally tabu and the smell, which everyone claims to hate but secretly love their own scent, and knowing the person probably shit hours before your penis was inside them.