Looks like it's mating season.

The lizardman's nostrils blew a gust of hot winds as he snarled in discomfort. He grasped his head and shook it.

At first Sophia and Regina thought he was fighting from within, but then they noticed that the front of his pants started to bulge forward.

The sound of something tearing echoed through the lab. Punching through the thick denim stood an erection.

No, scratch that, two erections.

Bright pink, standing out in a curve, where two massive cocks stacked horizontally.

Under their gags, Sophia and Regina starred. Sophia looked at Regina, giving her a rather angry face.

If she wasn't gagged, she probably would have yelled "Was there snake DNA in that serum, wasn't there? Why would you put snake DNA in that serum?!"

Then Regina would have awkwardly remarked "well, snakes have a pretty unique musculature and I figured that it would help with fortifying newly regrown limbs and..."

"Tell that to the mutant!"

With the discomfort gone, the creature that was once Mark licked its chops as both cocks twitched.