The Mobility Denial System (MDS) is a new form of non-lethal weapon developed by Southwest Research Institute (SwRI) for the U.S. Marine Corps. It is an extremely slippery viscous gel that can be sprayed onto surfaces to make them all but impassable for six to twelve hours.

It is adherent, so it can be sprayed onto vertical surfaces as well as the ground, and also sticks to feet, wheels, etc. that come into contact with it. Its foreseen deployment is in creating temporary barriers to stop or delay crowds or vehicles.
This is a marked improvement over similar systems that sought the same objectives by using sticky stuff; those could be readily thwarted by covering them with dirt, newspapers, boards, etc.

Capt. Andrew B. Warren, MDS project officer for the Marine Corps states in pleasant military prose,

"Riots, protests, noncombatant evacuations, and sanction enforcement are just a few of the situations where this kind of tactical barrier would be most useful. The substance severely reduces surface friction and results in a loss of traction or control."

SwRI hasn’t released the formula for the Mobility Denial System goo, other than to say it is non-toxic, water-catalyzed and water soluble. It's possible that banana slugs were involved. This is a system that is ready to go, either in a backpack sprayer model that will cover 2,000 square feet, or a truck-mounted version that will cover 100,000 square feet.