I have a pretty simple routine; I lift few cases of beers every week. At night, i'll lift one by one that is slightly open at the top, and take a sip. Once all reps are done with that set, I crush between my hands and toss in the trash can to practice hand-eye coordination.
Continue doing this till you can't feel your fingers/other body parts.

You'll def feel the pain the morning. Let me know if this works for you guys.