Surprise Body. Pronounced "sib." A girl whose body is a lot better than you thought it would be without clothes on.
From Aaron Karo's RUMINATIONS (www.AaronKaro.com)
-I love hooking up with SBs (pronounced “sibs” and short for “surprise body”). There’s nothing like taking a girl’s J.Crew rollneck off and discovering that underneath all that wool was a six-pack and two cannons. My first reaction (that is, after exclaiming “Yahtzee!”) is to suck in my own stomach, which suddenly doesn’t look so hot in comparison. Often times, a SB is also a “wideclops” – a girl whose eyes are too far apart. You can tell you’re talking to a wideclops when you can only look her in the eye one at a time. This is of course very distracting – which is why later their bodies are such a surprise.