…That is the question. ThinkGeek is selling that on a t-shirt for the "regular expression junkie + lover of literature." Wearing that around would be a sure way to get me to notice you, especially if you have a nice rack or happen to be Angelina Jolie.
Note that the parentheses are unnecessary except in the case of Perl-folk wishing to avoid using the naughty
$& variable for performance reasons. Also, the expression is buggy in that many alternatives to "bb" are not matched, so it would probably be better written as simply
var answer = /^bb$/.test(i);.
Alright, I'm done debugging the shirt now.