PFP By Mizz-Britt on DeviantArt.

About three months ago, you willingly volunteered for Undyne and Alyphys’ feeder experiment. In that time, you’ve gotten absolutely massive, they’ve fed you tons of fattening food all day for the last few months. Both of them have also gotten very fat and gassy themselves.

You’re sitting your giant blob ass on an entire bed, yeah, you’re so fat your buttcheeks take up an entire queen sized bed. Suddenly, the door to the room bursts open, in walks Undyne holding a giant pile of junk food.

Undyne: “NGGGA-Burp-BUUUUUUURP!!!-AAAahh! Huff, ugh… Hey, punk! I got more shitty food for ya!”

Her sweaty belly glistens in the light of the tv (which has Mew Mew Kissy Cutie 2 weight gain fanart playing. Not your selection, obviously).

Undyne aggressively swallows a burger whole and belches before slamming the pile of food into your giant, jiggly thigh.

Undyne: “OPEN WIDE, PUNK! BUUURP!!! Ugh…”