Oh DEAR GOD! That is hilarious but extremely embarrassing (Because they're so unaware). If it's quality sushi than you should eat it as is, or apparently you don't like Sushi you like Soy sauce.
My girlfriend also enjoys dousing her rice in soy sauce.
When I was in Hiroshima I ate Okonomiyaki... I didn't really slaughter the way the meal is eaten but I didn't enjoy it ... but I couldn't throw it out because all the while I was having a conversation with the chef!
Needless to say I ate it and then had to excuse myself to purge the demons.
(Could be the combination of noodles and that damn Japanese mayo.)