a whale of a (good) time
An exceptionally fun, exciting, or amusing experience. (Usually used in the phrase, "have a whale of a (good) time.") Gee, Samantha, I sure had a whale of a time at the dance with you last night. We should go out again sometime! Come out to our party this weekend, it's sure to be a whale of a good time!
whale of a time
A very enjoyable experience, as in We had a whale of a time in Puerto Rico. This idiom alludes to the largest mammal to describe something very large and impressive. [Colloquial; early 1900s]