Now this was a huge laugh for me: the Dekochari!

Dekotora is an abbreviation for Decoration Truck (Torakku). Chari means bicycle, so mixing it up with the Dekotora abbreviation it becomes Dekochari! Dressing up your bike into a Dekotora is just hilarious!

The soundtrack is called Ichiban-boshi Blues (by Bunta Sugawara and Kinya Aikawa) and the footage comes from a video called Dekochari Yarou.

If you thought that wasn't funny enough, how about the Dekochari at 0:26 being driven by Daijiro Inada?

And how about another one just for the road? :P