For instance, I loved this one:
"I could have sworn that was an aspirin I took this morning".
He said that in the elevator when Daniel - as the ascended being - showed up asking for Jack's help with some urgent matter.....but Daniel is powerful, but unable to actually do anything to help in this crisis.
Hint: There are sayings of Jack O'Neill in Stargate SG1 somewhere on this website if you look hard enough. You can use one of those quotes if they are a favorite of yours or you can remember the quote all by yourself.....

Have fun!