look up any word, like ratchet:
 
1.
used to mention a friend or elderly mate.
Originated from England pre 1930s.
Tally Ho Old Chap!

Oh my Old Chap, it seems the elephant has destroyed our tea house! What a rotter!!
by EvilBoris October 28, 2005
 
2.
ones front-mounted, downstairs tummy banana.
"how's your old chap been since the cat got at it?"
by Dutts March 01, 2005