Definitions by https://yourmom.com

hMmf 

When you’re mad at someone and have no comeback so you say “hMmf”. It can also be used when you’re angry or disagree with someone.

mason: “i’m not going to your game”
peyton: “hmMf”

hMmf by https://yourmom.com March 6, 2020

hMmf 

When you don’t get your way, someone {disses} you or someone disagrees with you and you’re mad about it. You say “hMmf”.

chad:“You’re ugly”
Sarah:“hMmf”

hMmf by https://yourmom.com March 5, 2020