Quad penetration 

Insertion of 4 items into an orifice or receptacle. The items inserted are generally, but not limited to, male genitals.
For when DP just isn't enough.

The wife and I are going to push the boundaries today. We're trying for quad penetration...

Quad penetration by Big Pimp Daddy April 14, 2006

Quad-Dildonic Penetration 

Noun: Penetration involving more than three and less than five dildonic objects, generally dildos, or in the classic western form, dildi.

Last night Jill had some crazy quad-dildonic penetration

Quad-Dildonic Penetration by The baddest mofo who wants to be a pilot July 7, 2008