When two people are having an argument and one says "Mum Fat" to break up the argument.
Kid 1: Why are you so mean?
Kid 2: No you
Kid 1: Stop annoying me!
Kid 2: Or what
Kid 1: Mum Fat
by Gink111 September 11, 2019
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"ur fat mum" Is an insult. usually, people are just joking around, but it offends some people.
by That One Guy In 2nd Grade March 8, 2016
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1. Asian Chuck Norris.

2. RuneScape legend, tank, and god.

3. A mythical beast from Sorrow of Knights who can tank 399 RSD opts easily, and is the #1 f2p BSer in RuneScape.
1. Person1: "What happened to your face, Edward5010?" Edward5010: "I got fat mum clubbed".

2. Person1: "Hey Edward5010, off to church again?" Edward5010: "Yes" Person1: "Don't bother. Not even divine intervention can stop fat mum club from kicking your ass."
by fasterlouder November 24, 2010
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