When a thing or song, normally a video from the internet or a website, gets around the school very quickly.
It suddenly gets very popular for about 1 month then gets out of fashion.
"Hey bill have you heard of Numa Numa?"
"Please that was a "school fad" months ago!"
"Urban Dictionary is such a school fad!"
"I love "put a donk on it!"
"Oh my god that's such a school fad"