My first encounter i freaked out and it didn't go well, nothing that i couldn't get fixed with a little effort but needless to say anything that involves handcuffs is bad. However ever since then I've always played it kinda cool, in fact my last encounter with a cop involving weed was me smiling and waving to one as i had the end of a blunt hanging out of my mouth. He smiled and waved back.

edit: remembered a recent story my brother told, and i had to share it. He was hanging out at his college orientation meeting a few people and smoking bud, and they saw these kids sitting in front of the frigging college sign and smokin a j. Him and his friend saw the cops noticing these kids and tried to warn them as they didn't want anyone getting in trouble at the school before school even started. This ends up evolving into like a 20 minute on foot chase that ended in my brother and his friend ninja'ing down this 15 or so foot wall and losing the cops. Wish i could have been there to have seen it.