Pick a song, and re-write the lyrics. Make sure your new lyrics line up correctly with the song, as far as syllables and length go. And you don't have to do the entirety of the song, just a verse or the chorus.

thats me with the ex lax.
thats me on the toi-let, losing my constipation. (rem)

i tried so hard to not take a leak, but i have an overractive bladder. (linkin park)