Upon which the American (naturally) challenges him: "Oh YEAH?"
The Russian says, "Sure! Here, Yuri! Jump off the deck (into the freezing Atlantic) and swim around the ship!"
Yuri marches off without a word, and does as he is told. The Russian turns around and says: "See, there's an example of courage!"
The American has to top this, so he calls up one of his underlings and gives him the order:
"Jack, Jump off the main mast into the ocean, and swim around the ship seven times!"
Poor Jack goes off without a murmur, and he too does as he is told. The American General says: "Now top that for courage!"
So they both turn around to the British General who has been standing around watching these antics silently. They ask him: "What about your people?"
So the British guy calls up one of his people and says: "Trevor, jump off the mast and swim under the keel of the ship, will you, old chap?"
Trevor stares at his general.
"Let me get this right. You want me to jump off the mast."
"And swim under the keel"
"You must be daft!"
And so saying, Trevor turns around and saunters off. Whereupon the British General turns to the other two and says,
"Now there's an example of TRUE courage!"