Underground Hammer 

The act of have a finger shoved up a males ass while A) getting a blow job or B)Jerking off

She was blowin' the hell out of me and finished me off while giving me an underground hammer

Underground Hammer by Snaggeltooth 27 November 27, 2010

Pump with an underground hammer

getting a handjob while the chick jams her thumb in and out of your ass.

So im getting a handjob from this ten dollar whore and the next thing you know im getting a pump with an underground hammer .

Pump with an underground hammer by Dick Fitzwell Esq September 1, 2009