There were quite a few weird street pass phrases I got, so let me share a few. And sorry if they're from spot pass, I forget which were which.
"Lettuce be friends."
"I like turtles"
"Mathematical!"
"Burn Something"
"I take my leave..."
"Hello animals"
Ok, some of those aren't weird, just interesting. There was also: "Whoop-de-whoop" which I liked. And: "A mayor's job is never done!" which was clever. Also a few people didn't have a phrase, and someone used their email!
My uni friends change theirs all the time they range from Japanese, they don't speak a word of Japanese hah I've also had ones that are just plain strange and make no sense!