Need Help With A Glitch :-/

[BlackpoolJumper!]

any1 know the glitch on Dawnville (CoD2*) where u can like float underneath the map but with ur head slightly sticking out over the top ?? Saw a guy doing it on a public server, he was shooting loads of ppl with this glitch and they couldnt even see him

[josh43758]

I've did it b4 but im not sure how to do it. I think it somewhere close to chicken coops or something. If i figure it out i will repost.