Flies stink when they die!

[Big D]

This fly kept flying up to my monitor and I finally snatched it and squished it between my hands. I flung it away and wiped the guts away...but, when I smelled my hand afterward, it smelled...stinky. Of course, my hand may have already stank but whatever.

You know that flies sometimes eat poo, right? So those exploded guts on your hands may have been filled with half-digested poo, or something similarly unsavoury.
Which could well explain the odour.

I tend to pick at my fingernails, and sometimes toenails, when I'm half-asleep in bed. On the plus side, I rarely have to trim my nails; on the minus side, it's really not a cool thing to do.