My family was at Chuck E. Cheese (or Chunky Cheese as my DH calls it) and all the kids had their own drinks as well as those plastic cups to hold the tokens. Well they couldn't keep track of whose was whose, so I whipped out my Mini Sharpie and put their initials on them!
(By the way, if you are a member of the Chuck E. Club, you can get all sorts of good coupons!)
Then I started to think of all the other practical applications in similar situations that one could do: at picnics or anywhere serving in plastic or styrofoam cups, even paper plates! I could have it at the ready for kids initials on clothes tags, shopping bags (for when what's inside matters to a particular kiddo), Oh the possibilities! And with 24 colors, what could be better?
Just keep them away from the youngsters…we had an unfortunate incident not too long ago where the older sibling left one out and the younger sibling "maked pictures!" on every horizontal and vertical surface she could reach in the kitchen! (Doesn't come off good from glossy paint…7 coats later, you can barely even tell!)
Where do you use your Sharpie?