I can't post anywhere

I just love the way a simple expression can disprove itself.

Like "All Cretans are Liars"? "Ceci n'est pas une pipe"? "The set of all sets that do not contain themselves [does]/[does not] contain itself"? "For a theory T, Goedel sentence G = 'G is not provable in theory T'"? I got a million of 'em...