I'll go first. Mine is the instant knockout drug. Like Dexter's intramuscular injection that causes someone to immediately lose consciousness. Or in the movie Split where there's the aerosol spray in your face that makes you instantly unconscious. Or pretty much any time someone uses chloroform.
I just saw that in WandaVision. Darcy is an Astrophysicist but was also hacking through various firewalls to get at some secret data.