The great thing about the internet: when you don't get an inside joke, you can just google it.

http://www.google.com/search?q=airspeed+velocity+unladen+swa...

Second link.

Both Google and WolframAlpha answer this question almost instantly, without soaking up the fractional attention of dozens/hundreds of human readers here. Always try the simple automated query first: it's the only polite/efficient thing to do.

It probably says a lot about my social circle to think that I was actually horrified that there are people out there that wouldn't get this.

Maybe I should talk to a shrink... Or anyone else who didn't do science or engineering at university, for that matter.

It's a Monty Python reference.