Transformed into a pile of blubber similar to Sonya!
"Oh no!" Sonya gasped, "I'm so sorry! Are you okay?"
Derek, or rather Denise at this point, had turned female. Whatever clothes he (she) was wearing before were gone now, nothing more than shreds of cloth on the ground. His (her) hair had lengthened out, his (her) facial featured turned more feminine, and he (she) had a pussy rather than a dick.
Denise, as she was now called, had an overlarge belly similar to Sonya, albeit comparatively smaller. Most of her fat seemed to settle in her ass, hips, and thighs, making her more pear shaped. Her and Sonya shared similarly sized breasts it seemed.
All they could do for a moment was stare at each other while they processed what was going on. Denise was okay, Sonya was relieved but still had the niggling fear that she was responsible for this somehow.
That's when they both started feeling the need to release another metric ton of flatulence, and there was no way in HECK Sonya's little bathroom could handle both of them. That's when the strange idea came into their minds to stick their asses out the windows to relieve themselves. They hurriedly waddled over to the windows, opened them, stuck their asses through, and proceeded to do just that. They continuously farted for over ten minutes until the air in their guts finally died down. They felt good. Denise felt it would be a good idea to turn around look out the window, perhaps to see if anyone was watching...