Put this one under the “weird but hilarious” category. This is a machinima music video by WAM Studios in which G-Man sings Body to Body by Jay-J. It was created with Half Life 2, lots of Faceposer and GMod.
The song is pretty much horrid, but the video rules because they re-created the original music video by Jay-J almost perfectly, only with G-Man and Alyx in the leading roles. Seeing G-Man act suave and sexy is worth the price of admission on this one. Be warned it has a few images that are more than likely NSFW, especially the original, which I recommend suffering at least a few seconds of in order to fully appreciate what was done here.