Onomatopoeic term for 'ñ', the 17th letter of the Spanish alphabet. It is pronounced as in the 'gn' in Cognac and also as in the 'ni' in onion. It can be reproduced in the common PC keyboard by pressing ALT and 165 on the num locks for the upper case letter and ALT 164 for the lower case letter.
Did you know that an eñe is just the letter n with a silly line on top?
It's called a tilde, you ñoño!