Sodium is a constituent of farts, mainly non-smelling ones. Its name comes from "So did you ... um ... ", which soon became "sodidyou...um", and then later simply "sodium". The chemockal symbol of sodium, Na, comes from the answer to the question "So did you...um..."; which is always "Nah...!"
Sodium is also involved in the body's production of pee; when burning, sodium gives off a bright yellow (that's pee-colored to you and me) light; this is cause by the dee-lines in sodium's rectum; dee-lines are pretty much the same as detours, so if you pee, it's just a tad of your sodium taking that yellow detour.
Sodium is very reactive; if released into a toilet and the seat of the loo isn't subsequently lowered, violent reactions may occur in girl-rich environments (also see yaddayadda-complex and fartknocker).
Pretty dang bad, especially if you happen to leave that seat up on the loo, buddy...!
Isotopes of sodium
Isotope is some greek gibberish for "same place": In the same place as sodium (as a constituent of pee) is poo, so poo's gotta be an isotope of Sodium, right...?