I'm going to tell a first-time sushi eater that the wasabi is guacamole
Holy Cow! How do you think they are going to react?
I think it's going to be an angry reaction once the heat hits their tongue.
Telling someone that wasabi is guacamole is a mean prank. They could get hurt because wasabi is powerful.
Their reactions are funny and that's exactly what I am hoping for.
Substituting peppery wasabi for guacamole and not explaining it to your friend is not nice and it's not funny. Find a less aggressive and cruel way to get your rocks off.