Boas are a type of snake that are members of the Boidae family. Boas are basal snakes that are "primitive" in evolutionary terms (i.e. less derived). They are constrictors and most give birth to live young.
It's not the word for surprise, just the exclamation you might make when getting surprised. And only kids and teens would use it, it's very informal. --- ColonelWilks: Wow. That was uncalled for. It's that kind of immaturity that makes me realize just how bleak the future of our fine nation looks.