tons-o-fun Share definition Flag A quantitative measurement of fun dealing with an amount of fun that is over 2000 pounds or more. Usually used sarcastically. I told Megan that talking to Doug and Josh sounded like tons-o-fun. tons-o-fun by Matt March 9, 2005 0 0 Get merch Get the tons-o-fun mug. Buy Now — $32.95 See more merch