A person seemingly unable to exchange simple pleasantries such as "hello", "how are you", and "goodbye". Often someone encountered only briefly (i.e. a cashier) but they may also be someone you see every day, such as a co-worker.
I just went to the drugstore to buy some toothpaste, and ended up having a one-sided conversation with the cashier.

Normal Person: Hi, how are you?
Mute-ant: ...
Normal Person: How much for the toothpaste?
Mute-ant: ...
Normal Person: (reads register and pays) Thanks, have a good night, you fucking mute-ant.
Mute-ant: ...
by ACNY November 18, 2009
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