My favorite comes from the episode where Kirk and company were trapped on the planet, and Scotty had taken the Enterprise to investigate a distress call ("Friday's Child", I think).

In fact, oddly enough, I just used this phrase last night to explain my actions in a certain situation.


Fool me once, shame on you.
Fool me twice, shame on me



That, and every now and again I pick up my computer mouse and talk to it....

Anthony

You can lead a horse to water but you can't make him think.