Right now we can't...anywhere. It used to be a long time ago(before it was called the Internet) that programs existed that allowed one to select from a group of signatures or to append what was called a tagline(now called siglines). It generally made even the nastiest of flames tolerable when you saw a funny tag at the end of the message. Sadly these have disappeared on the WWW. I got a great deal of enjoyment out of them, I even moderated a thread that was devoted exclusively to posting and rating taglines.
here are a few of the best...
"It's Ensign Pillsbury...He's Bread Jim!"
"Jesus Saves! Passes to Moses, Moses back to Jesus, He shoots! He Scores!"
"I'm in a phone booth at the corner of Walk and Don't Walk."
"I'm a lawyer." "Honest?" "No, the usual kind."
"Heh, Heh We're Crime, and everyone knows... Crime doesn't PAY!!!"
there are more, some folks like to use famous quotes from the theatre and film, others will dig stuff up from books. Personally I think the best are made up.
My all time #1 favorite tagline was made up by my son...
"Luke...I am your father! (pause) Let go of my nose!" - Darth Vader
David Weed
aka the Bird of Prey
www.warp-drive.com