1. To completely screw someone over in a business deal.
2. To make great promises to a customer and then deliver subpar work.
3. To pretend to be faithful to your spouse and then cheat on her mulitple times.
"Rod, you were supposed to split the retail profits with me 50-50! Don't Helmick me!"
"Rod, why are you charging me for this consultant work that was entirely lousy? Are you trying to Helmick me?!"
"Rod, are you really doing your marriage any good by having sex with hookers in New York, while your wife is home taking care of the kids? You shouldn't Helmick her!"
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.