An insult against a group of people who are being stupid and you're not a part of it.
This is a reference to treatment of sludge generated by wastewater facilities, the pump gallery is where you watch thickened concentrated sludge be digested by micro-organisms.
Bob watches as cars continuously slide down an icy road and crash after not heeding anybodies warning or slowing down.
Bob "feels like im in the pump gallery for the sludge digestors"
You begin by combining your cum with cow shit. You then freeze this newliquid into solid form. You finish by telling a friend that is a new type of ice cream. Warning: only allow friend to eat 2 scoops - anymore is considered deadly.
When Mike pulled The Silly Cow Sludge on Kevin, he forgot the twoscoop rule and thus killed Kevin