Very subtle short form of “your mom”/“your mother”, originally part of a knock-knock joke. Similar to “Joe”/“joe Mama”, the casualty does not have any idea that they could be spoofed (unless they know the joke, of course).
“Knock-knock!”
“Who’s there?”
“Ermo”
“Ermo who?”
“Er mom!”
“Bro, I had an amazing night out with Ermo yesterday!”
“Nice! But who’s Ermo?”
“Er mom!”
“Who’s there?”
“Ermo”
“Ermo who?”
“Er mom!”
“Bro, I had an amazing night out with Ermo yesterday!”
“Nice! But who’s Ermo?”
“Er mom!”
by O Rei December 16, 2022