You should have inspected him closer - he may have had a tab of yaba stuck between his teeth.
On a more serious note, my boyfriend is into poppers, and I always start to feel a bit of a buzz after he takes his second or third snort. It doesn't bother me at all when he's on the bottom - but he was on top one time and dripped that shit right in my eyes. I hung in there like a champ, but stumbled around the room blind afterwards like Mister Magoo. I felt like kicking him in his ass.