Hello @Sadten and thanks for your post. This is a great question! I do not work with food/drink so maybe someone using a kitchen printer may have a better answer for you...
The only item that Square POS could print during a transaction would be a printed receipt. If you are using Square for Retail you can print barcode labels, but I don't see that helping much here, so there could be a few options...
When someone buys someone else a drink, you could assign an Item called BEER (chip) or Whiskey (chip) and add that to the sale. Then you could print out a receipt to give to the recipient, which they would redeem. The problem is you'd have to do a separate transaction for each person that was bought a drink. When the receipt is redeemed, you could add another item to the sale called BEER (free) or Whiskey (free) which would have been assigned a price of $0 zero dollars.
Another option would be to create barcodes that would be printed on a card or label which would be assigned to an item that you want to comp, so the inventory item would be $0 zero dollars. In reality this is really just another form of a physical chip, but if you want to track or barcode scan for ease of tracking, this could allow you to do that.
I know these are not ideal solutions, but this is what I could figure out for you. Some other ideas if you're using a Square Register could include adding your customers to your customer list, and when a drink is bought for someone, you could bring up their "account" by name in the Register and make a NOTE that they are due a free drink. When they would want to redeem it, you would find their name in your customer list, and delete the note about the free drink. Also not ideal and would depend on how busy you get and how much time you want to spend on tracking these transactions.
