The mining pick gains a special alternate attack when the Psycho Outfit is worn, using an animation that is identical to that of the Spiked Bat alternate attack.
Main: Tap / and Chuck will raise the mining pick up over his right shoulder and swing it in an arc down to the left.
Combo: Quickly tap / and Chuck will raise the mining pick up over his left shoulder and swing it in an arc down to the right. This is a mirror image of the main attack.
Alternate: Hold / and Chuck raises the pick over his head and swings it down, dealing significantly more damage and with potential to burst a zombie's head.
The alternate attack used with the mining pick is possibly a reference to Harry Warden from My Bloody Valentine, a Canadian slasher film about a deranged killer murdering those who dare to celebrate Valentine's Day. In the film, Harry used a mining pick for his signature weapon of choice.
In the Off the Record PC files, items.txt reveals that there is a weapon called "PsychoMiningPick," probably for the Psychopath Skills Pack, which has exactly the same appearance as the mining pick.