My favorite Latin expression is "sic", even though it can only be used to make other people seem un-smart, thus making you seem like a jerk for using it. "sic" is used when you quote someone, and it means "This is not a mistake I made while quoting; I am quoting a mistake the original speaker made". For example:

[qq=Meat Puppet]I always though it meant egzample [sic].[/qq]

I use it there to indicate the use of a word that doesn't exist. See, it makes me seem like a huge jerk, especially if I was engaged in a debate with someone; using it repeatedly would basically be a very subtle attack on the other person's intelligence / grammar skills.