ROFL
I have had this observation for quite a while, and those who speak to me on MSN regularly shall be less than impressed, but a topic is a topic, and so here goes.
Beware of people who are fond of typing "ROFL" (abbrev. Rolling On FLoor Laughing) in IM conversations, as these people are Heinous Liars. Obviously, if they are at the keyboard typing "ROFL", then they cannot possibly be doing what they claim to be doing, i.e. rolling on the floor laughing, since both the act of rolling on the floor and the act of laughing combined makes it nearly impossible to be typing simultaneously. Ergo, they lie. In certain circumstances, however, the person may not be lying; e.g., if they are typing on a wireless keyboard chained to their upper torso. Apply discretion.
Be even more wary of people who use the extravagant variant "ROFLMAO" (abbrev. Rolling On Floor Laughing My Ass Off), as apart from the impossibility of the abovementioned logistics of rolling on floor while simultaneously typing, it is a scientific and proven impossibility that even the most excessive amounts of laughter will not result in the dislodgement of one's posterior from one's body.
The world is full of cruel, vicious liars, my friends. All I ask is that you (speaking of physical impossibilities) watch your back.