"Pump up the jam" is an anagram of "jam up the pump"
If you wanna hear something hilariously bad, check out Sondra Prill's "unique" cover of this song. It's basically her shouting the lyrics at a bunch of people on the beach, and was so awful she's tried to have it scrubbed from the internet. To no avail, of course.
When this video was first broadcast, audiences feared it was real, and that jam would be pumped into their homes through the screen
"Feared"!?