PPAP stands for pen pineapple Apple pen, which is a dumb-ass YouTube video which for some reason went viral. You can watch it yourself if you want, but I wouldn't recommend it.

A term used from a popular Japanese song that stands for Pen Pineapple Apple Pen.

PPAP is a Japanese video, where a man in a yellow suit talks about a Pen Pineapple Apple Pen, while instructing you how to make your own PPAP.

Pen Pineapple Apple Pen. It's a song that went viral for some reason.

stands for "proud producer of apple products

PPaP is a meme that is found on the site of YouTube

A song of a japanese person in leopard print clothing awkwardly dancing while singin
here are the Lyrics-

I have a pen...
I have an apple....
UGH
Apple pen..
I have a pen..
I have pineapple..
UGH
Pineapple Pen
Apple pen.... Pineapple Pen....
UGH
Pen Pineapple Apple Pen (PPAP)