i used to work as sales , once a customer from the country side called me asking angry:

why i don't have a cup holder , and the discussion went for more than 30 min.
and he was talking about the cd-rom drive lol
he saw it opening somewhere at store and he thought it's a cup holder.
that was crazy.

and another customer when pentium II was first to market , he came to our company asking for a
"benetton 2000" insteaqd of P II .
when u work in sales we are used to these kind of poor knowledge peeps.
the hard part is to control ur temper and try not to fall down from laughing.