I hate to be a Negative Nancy but please, Japan, and I can't stress it more...
ENOUGH WITH THE MAYO.
Mayonnaise is not an acceptable pasta sauce. It just isn't. It's just, just no. Stop.
On a better note, attempting to explain the history of the YMCA when your host father sings it at karaoke is a more difficult task than you think. Singing Lady Gaga at karaoke though will undoubtedly wow your Japanese family.
(Why didn't I start a tag for 'mayo' sooner? It seems to be the most recurring topic on here, sadly)