This word is essentially the exact same as fantastic. However, it is the word "fantastic" that is more "Jeff" oriented, any one named Jeff, Geoffrey, or Jeffrey is fine. If you spend a day with someone named Jeff or Jeffrey, and you had a good time, you had a "Jeff-tastic."
A good example of using this word in a sentence is "Wow, I had a Jeff-tastic time with him!"
by Jeffoh1990 July 30, 2009