Quoted from ramegoom:
This was an interesting find.
I bought an old dollar slot machine from a guy who didn't have the keys for it - but assured me it had Ike dollars inside. Insisted there was at least $150 worth of coins in it, so I bought the machine for $200. Didn't really believe him but thought it's worth a shot.
Got the monster home, drilled the lock and wouldn't you know, $183 in Ike silver dollars inside! Yesss..scored!
So I emptied the hopper and after I counted them, dropped them back in. For whatever reason, one of the coins made an odd sound when I put dropped it on the table. Singled it out, started examining it, and realized it was hollow, so I used a knife. Sure enough it was a hollowed out Ike dollar, looks like it was very carefully machined. Nothing inside, but looks like there was enough room to put another smaller coin, or maybe a memory card. Totally weird. First image is that coin next to a regular Ike dollar.
Here's the coin opened up:
I definitely saw those for sale in a Head shop in the late 70's when cocaine was big.