when you want to doodle, but your pencil's eraser is old and terrible, and you don't have a replacement on hand... 
works great, tbh!
Omg life hack tho lol
it's one of those nice plastic-y feeling smooth sorts of erasers, rather than the crumbly rubber-and-fine-sand Pink Eraser type ones... which is like the original eraser used to be. the rest of the block eraser is going to just live on my desk here, in case it needs to be a donor again, or if I actually want to use it, lol.
I mean, the original eraser for this pencil was the smooth, fine plastic-y sort too.
