you know he would probably go all in with 77 as well, I mean it's a set
he would probably also go all in with KT, and possibly T9 and AA
lots of hands you beat
especially since BB is a weak player that will bluff with random crap

also, if the pot is $11 and it costs you $3.5 to call, you don't need to win even half of the time, I think one quarter of the time or so and your call is justified