A question

I was wolf-whistled today, which of course will induce ripples of laughter around the globe, so you can keep your comments to yourself (although I know that for some of you this will just be too good an opportunity to let go...). But what I want to know is when I try and do it, why do I look like a hamster with a bellows up its arse? And why can't I make any noise whatsoever?