There are multiple ways to approach this I would say arrange it when you meet up with friends if not then the classic method is face to face have a good conversation going and then just slip it in at the right time, if not a text.
But I will go with ranlo and just take a good chance and try to find the right time.
Really? Does this crap actually work nowadays? At least with a phone call, there is effort behind it. Sending a text takes very little effort. Hell, I just sent 3 while typing this out. BTW, none of them meant anything. One of them was in fact a facebook post.