Ian and the Swat Helmet
Created by: Hykos
If you attempt to put a swat helmet on Ian, you get the message, "It doesn't seem too keen on wearing that item," and it remains in your hand spot. But if you open up Ian's inventory again, you'll find that it's equipped, but not showing on his sprite. You then can remove it from Ian, causing it to appear on the ground under him, and also while you still have it where you last put it (hand slot, helmet slot, a table, etc.) If you move it while it's not equipped the other helmet disappears, unless you equip it first, then you get a full hand slot. You can open up the hand slot by clicking a table, which places a helmet with no hand ui icon sprite.
Edit: Tried this with the captain's helmet, also equipped as the space helmet while getting the same not too keen message.