what are some responses to "I like this guy" or "there this guy thats really cute..."

[thefranchuse]

i was seeing this girl who kept bringing up other guys she was seeing.

what are some ways to respond to "Dave (other guy she mentions) is so funny blah blah" or "that guy at the party was really cute/fun"

I mostly just nod and not talk for a while...or ill change the subject but i found that both of those approaches are not appropriate.

any help? i have been struggling with this for a LONG time.