Buy you ice-cream?
"...Your laughter is infectious, which is probably why I enjoy making you laugh. I think you have the propensity to put everyone in a good mood. (I’ve been pretty perky the last couple of days). I must admit though, that when we were in uni, I was slightly intimidated by your quietness, and therefore didn’t make all that much of an effort to talk to you. I only wish there was more time during the trip to get to know you better".