AKB48 is the most popular group in Japan (read, make the most money... not sure how they calculate but anyway). It was started some years ago in AK
ARA with about 48 teenage girls, to promote business (Akihabara is the place in Tokyo where they sell electronic goods). Now there are groups in Osaka, Nagoya, etc called OSA48, NAG48 or whatever, I cannot keep track of all these teenage girl groups...
Soooo these three boys at university are playing off that girl group theme