Short for strap on. A strap is a dildo that attaches to the waist by harness. Straps are not just for lesbians, they're for anyone who wants to fuck their partner with a dildo. See pegging for more info.
1. The act of bodily penetration with an artificial phallus.
2. The sexual pleasuring, or punishment, of one's partner with an artificial phallus.
3. Givin' 'er what she(he?) deserves with a fake cock.
4. Emasculating somebody.