Christina Applegate
Samantha Who - Sam and the Pina Colada Song (Rupert Holmes)
http://www.youtube.com/watch?v=1sCoAKQg6u4

Why? The Pina Colada song was in both her movie "The Sweetest Thing" and in the pilot episode of "Samantha Who?". And someone already made a clip on youtube with both of them edited together.

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Nick Offerman
Shabba Ranks is Mr. Loverman
http://www.youtube.com/watch?v=g8BOZyaMrn8

Why? Change it to : Mr Offerman - Swanson!

Edit: I'm not sure why I think of shit like this either.