In a coon's age
"In a coon's age" is an American phrase meaning "in a very long time." In a coon's age is an Americanism recorded in 1843 and probably related to the old English expression 'in a crow's age,' meaning the same. The American term is an improvement, if only because the raccoon was thought to live longer -- up to 4-5 years in the wild - than the crow. The expression may date from an earlier time in the 1800s when the exact age raccoons lived to was not known. They may live up to the same age as a dog in captivity.
Usage Example:
Jeff hasn't seen Ryan in a coon's age.
We've been waiting a coon's age for our [...] food.
From the "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Facts on File, New York, 1997), Page 168.
information found on http://www.phrases.org.uk/bulletin_board/5/messages/626.html