So you are railing a chick doggystyle and occasionally fall out and put it back in. After many fall outs your friend sneaks in from behind and replaces you. Let him get some pounding in and then you walk up infront of the girl and ask her how good your doing.
So my friend and I gave my girlfriend a Canadian stranger last night and she didn't like it at all.
This is an advanced manuever folks, and it takes teamwork. First, you being fucking your girl doggy-style in front of a rather large window. Then, you carefully have a buddy or yours swap in and continue fucking her without her knowing there's been a trade. The Canadian Stranger is complete when you walk outside and wave to her as she's being fucked by your friend.
"I can't believe she dumped me after Craig & I Canadian Stranger'ed her last night."