When two penises are interlaced and touch tips in anticipation of one ejaculating, the ejaculatory penis cums inside the other penis. Storing the cum inside the urethra, the cum is then recycled for the next round of ejaculation.
i.e. fluid swapping
Tom: "Man, I've been feeling lonely, makes me thing of the days when me and my hubby used to infinicum maneuver."
Barry: "Dang I've been feeling the same, never heard of that infinicum shit though"
Tom: "You've never heard of infinicum? Dude...what are you doing later tonight."
Barry: "Interlacing my dick with yours, I guess!"
An seemingly endless ejaculation.
"I banged Joe last night, he blasted my ass with his infinicum."