If you have a cart whose value exceeds your current money amount (ie a 300 dollar cart but you only have 30 dollars) and attempt to send it to another use via the gift function, the user will receive a notification that "[User] has gifted you their shopping cart!"
However, the gifted user will not actually get the items, and the gifting user will not lose the money / empty their cart.
Thus, its only consequence is that it spams the gifted user with notifications if desired, or potentially tricking a user into believing they were given items when they were not. It is rather harmless, although potentially annoying.
Images link:
https://imgur.com/a/XAuoP51
Another thing that I discovered, whether it is a bug or not, is that the cart will buy items that it can afford, even if the entire cart costs more than your money. This can be seen by watching my money account, as after my first purchase my money goes down the cost of the ring, the ring is removed from my cart, and given to my inventory. (seen in the second/third image)