The baby medusas made my presents not spend for a while. I was joining a game someone was playing, I was player 2 and playing online. After I ran into a baby medusa, it ran into me again, then I went to use a present and it identified the present, used it, but the present stayed at my inventory. I managed to repeat this by hitting baby medusas, both yellow and purple types, a few times, and then trying to use presents, identified or not, I could use them infinitely for a while. I am not sure what made they go back to being expendable, but hitting baby medusas a few times brought the glitch back as much as I wanted. Also, if I hit the baby medusas while the presents were in this infinite state, they would randomize appearance, go back to being ??????, but they were still always the same present.