Brando: You know, I was riding a bicycle? that I made myself? 
and I was with Wally Cox and, God, I miss that good man! 
He had fingers like a sailor. [Marlon bends down and takes off his pants] 
I remember one time in Bangkok... [He now takes off his boxers] 
time buzzer rings. 

The taking off of his pants come from reports of his behavior on the set of The Score. The final "You- you- you're a squawking parrot, you're- you're an ant. " line, I believe was some spur of the moment improvisation Marlin did while shooting a scene in Apocalypse Now. I recall seeing it in one of the documentaries on the film. After he says it, Coppola throws a fit. The implication is they have done a million takes and Marlon just wont stick to the script.

After doing a little more research, the Wally Cox reference concerns an old Hollywood rumor that they had a gay love affair.