I came across this site which has a collection of dreadful/funny trumpet clangers.

Check it out!

http://www.billandellie.com/sounds/TrumpetBloopers.asp

The Polovtsian Dances one makes me laugh, but not for the intended reason - so much for the website author's 25 years in the business. I presume he's laughing at the handstopping - I suggest he gets hold of a score and has a look at what's written.