mc5 - I'm not wearing any pants!

Take a familiar (or at least famous) quote (e.g. "Don't go around saying the world owes you a living. The world owes you nothing. It was here first." by Mark Twain). Then find a good stopping point (e.g. "Don't go around saying"). After this, add the phrase, "I'm not wearing any pants (e.g. ""Don't go around saying, "I'm not wearing any pants!").

Stevie

I've already told the story in another place in which a pair of Birmingham constables, confronting my friend at a particularly trying juncture in his stag night and threatening to run him in for being drunk and disorderly were tersely informed "I'm not drunk and I'm certainly not disorderly. I just haven't got any trousers on".

Geo

"Ooo eee oo ah ah ting tang walla walla bing bang ooo eee oo ah ah ting tang walla walla bang bang. I'm not wearing any pants. Ooo eee...."

G Formby

"I'm leaning on a lampost at the corner of the street, and I'm not wearing any pants"

Kim

[G Formby] Presumably that's in case a certain little lady comes by...

Stevie

England expects that every man will be wearing pants when we engage the French even though I personally am not. Now kiss me Hardy.