I apporached 2 girls in a club and asked them to help me choose a gift for a girlfriend of one of my friends.

Id had some success with this approach before. The girls in question very quickly blurted out vibrator and laughed.

I wasnt sure how to proceed from here. Should I positively validate their choice? or should I laugh and then throw out a neg. Should I steer the converation onto vibrators? (this is actually what I did but they didnt realkly seem to get into the conversation). Personally I thought the conversation went a little too sexual too quickly.

So what should I do in situations like this?

Sounds like they gave you a shit test to see if you'd panic and turn shy! I would have said "I asked what you think she would want, not what you would want" in a cocky funny manner. Then steer the conversation away from sex until later on.