Do you sign up for liposuction when your pants becomes too small too, or would you then consider alternatives like buying a new pair, or maybe have them enlarged if you are too cheap/poor to afford a new pair?
Instead of bastardizing your lab equipment, perhaps you could something as radical as buying a slightly smaller egg stirbar (It's not like you need to feel inferior just because you don't have the biggest bar), or perhaps you could even buy a flask with a tad larger joint (and an adapter between 24/40 -> 29/24 so that it still will fit the rest of your glassware collection)...
(What amazes me most of all is that dozens and dozens of members have had this problem over the years - not checking the dimensions of the stir bar to see if it fits your glassware before buying it is like failing to try a new pair of shoes on before paying and taking them home...)