Percy long prong

Sparkling milk shake obviously.

I've Googled it and couldn't find a clear definition
Even duckduckgo returned nowt, although it seems to be the name of a South American pornography magazine
Urban Dictionary had something for bubbling, but that's an autosexual act so wouldn't make sense to sell

Well apparently the daily mail at some point tried to find out what it was at some point with no success either lol