Analysing Relationships
One of the best topics to tease friends about is the opposite sex (or the same, it depends). It also makes for lengthy analysis'.
The last few years have been pretty dry in that sense, and now I'm back in business! Ah, the pleasure to be derived from picking up a nascent relationship and teasing the hell out of a friend about it.
Also over-analysing it. The friend may either join in or get embarrased; either way its fun. This timepass probably wins over self-analysis (personality tests, zodiac sign descriptions and the kind). It covers airing and forming your opinions on acquaintances, following the course of various hypothetical situations, making predictions...simply designed to appeal to the human flair for drama and gossip.