Treat or torment your traveling companions with Karaoke! The Japanese are always willing participants so if you meet any on your travels ask them to take you to their favourite haunt and get ready for a cultural sing-off!
This is definitely a staple of modern Japanese culture. It is so much fun especially with a large group. Try and get to a Karaoke joint if you can. It makes for a very fun somewhat awkward night.
For more information head to Karaoke