kitty kitty kat kat kitty kitty kat meow but the me and ow have gotten w and m at the back and start.
It's also a way to piss people off when you barge into their home(s).
Here's a conversation using said word:
'mewmow uwu chan~'
'WILL YOU SHUT UP! YOU BARGED IN MY HOUSE AND STARTED TO SAY MEWMOW UWUCHAN FOR 10 HOURS! GET OUT!'
'no~'
'AAAAAAAAAAAAAAAAAAAAAAAAAAAA-'
Get the mewmow mug.