Being able to pull off a cover of a song by yourself and have it sound decent is quite a feat. Being able to cover a song by yourself, change the genre of the song, and still have it sound good is an even more impressive feat.
This dude takes blink-182's hit "First Date" and turns it into a ska song, complete with a saxophone and trombone. The lead guitar riff is turned into the brass melody and the guitar parts are changed from power chords to ska riffs.
You can check out Ska Tune Network on YouTube to see some other impressive ska cover songs.