I think it's from a bee. Honey bees accidentally rip their stinger and guts out after the stinger is lodged in skin.
I have to vote bee as well, but it's by design, not accident the stinger pulls out the insides. Besides, if it was scorpion, he'd still be in your pocket. It does help to know the location of these thing though, it really helps people pin-so to "entospeak" things down.