Once you're a good distance from the circus, you stop to catch your breath and immediately start gagging. What did that elephant jam down your throat, anyways? You try to cough, but it refuses to come back up - looks like it's too far down to get out. But what did it do? Trying to think this over, you suddenly start to feel a fart coming on and try to let it loose, but instead of hearing the "pblt" of the gas escaping and the sensation of it pushing through your cheeks, you hear a sort of muted "phoomp" noise. That's... weird, to say the least, but right now you've got bigger things to worry about than your gastrointestinal tract.
You decide to make your way home, and figure out what to do from there. On your way, another one of those weird farts comes on, again accompanied with a "phoomp" noise. After it passes, you notice that your pants are starting to feel tight. Did you put on some weight or something? You look yourself over, but you feel as thin as ever. Another fart comes on, another "phoomp". Now, your pants are almost unbearably tight. What the heck is going on? You decide to examine your ass, and as you look back at it you're sent into an immediate shock. Your pants are straining, barely holding together against the mass that is your rear end. You can see the fabric starting to tear slightly at the back, the flesh showing through it not your natural tone but instead a shade of grey, not smooth like it would normally be but more rough. Sort of like... an elephant! That must be what they did to you!
Having solved the mystery of what those things you swallowed were for, you feel another rush of gas coming on. You try to hold it back, and at first you manage to succeed. However, with every passing moment the pressure builds and builds, getting higher and higher, until it finally peaks at a point where you can no longer hold it back. Unleashing what should be the biggest fart of your life, you hear another, far louder "PHOOMP!" as your pants explode, your rear reaching at least three times its original size as a tail with a tuft of hair at its end shoots from the base of your spine. The sudden change is enough to throw you to the ground, landing on the cushion that is your now far larger ass, its thick flesh taking in the impact.
You aren't even halfway home and you're stuck sitting on the sidewalk of an empty street with the ass of an elephant. How are you going to get out of this one?