momik? mimik? (Insane, crazy, or kook customer?)

[Matthew Montchalin]

I run a motel on the Oregon coast, and employ a desk clerk of Aztec
extraction, and this clerk speaks Nahuatl as his native language, and
Spanish as his second language, and English as his third.  We quoted the
customer a price for three days, and encouraged the customer to inspect
the room, and after he did, he came back and paid the price.  About two
hours later, the customer comes back to the office and seeks a refund for
the second and third day, deciding he would only rent the room for one
day, and we rearrange the books to indicate that fact, refunding him the 2
days not stayed.  Rearranging the books is not necessarily a simple
matter; we require him to produce the receipt we just issued him; he
complains; he looks around for 15 minutes, making a scene, and then
finally 'finds' it.  We rearrange the books, cancelling the old receipt
and issuing him a new receipt reflecting the terms of the license (not a
lease) to enter upon the premises.

About two hours later, the customer comes back again, and this time says
he would like to pay for the second day because he'd "changed his mind"
again.  Fine, we ask him to produce his receipt.  He complains again.  He
eventually searches his car and produces his receipt.  We cancel it, and
issue him another receipt, this time indicating two days.

Towards closing time, he comes back and says he has decided on staying
just one day, and needs the second day refunded.  Fine, we go through the
same old rigamarole, and he leaves.

My desk clerk says then that customers like that, well, he calls him a
mimik or momik or something like that, and says that that is what a "kook
customer" is.  I can't find this word in Karttunen's Dictionary.  What is
the derivation for this word?  Have I written it down wrong, or heard it
wrong?  (I have only begun to read up on Nahuatl, and am put off a little
bit by the Spanish spelling conventions, so I naturally have a lot more
to learn.)  Any help to explain his choice of words to describe customers
that vaccilate, cannot make up their mind, or do not know what they want?