I found a stash of new Penn tennis balls in their metal cans!
I was visiting my friends school where he teaches and entered the storage closet where they keep their sporting goods. On a shelf were something like 50 new unopened METAL cans of Penn tennis balls. They've got to be from the 1980s. On the can, it says you can send in $6.95 with 2-proof-of-purchases and receive a Head Tennis Bag ($27 value). I'm tempted to open a can to read the details of the offer but I can't bring myself to do it.
I haven't seen a new metal can since I was young and just started playing. The last time I saw a metal can was just a few years ago when a lady and her young daughter came to the courts I was at and she pulled some used balls out of the can. I walked over to take a look then. I've seen them on that auction site too.
Back to using POGs. Why did I ever leave you dear friend?