First of all, the Cleopatra potato chips referred to in this slogan refer to a brand that existed at the time (it was discontinued for a while and then reintroduced during the retro boom).
The reason why Japanese high school girls learned about this is because kpop idols broadcast with their seniors and played the drinking game “Hello, Cleopatra!” that their seniors taught them.
It’s no secret that Korean otakus who didn’t know about this new trendy drinking game started asking Japanese Kpop fans what it was.