After getting cut down by a Captain's Shrapnel Launcher, I noticed a fist pump and a yell. I was pissed about dying, but started to think about potential for another modifier: Celebration.
Celebration: enemies excessively celebrate after killing a guardian. All majors will tea-bag, dance and/or do some pelvic thrusts to any orb after getting a kill. The lower tier adds (dregs, thrall, goblins) should point and laugh - perhaps fist pump and encourage the majors.
Maybe this isn't suitable for children, but I'd get a kick out of it.