Similar to a contraction but in lieu of a human baby, it is a shit baby. The moments before you deliver your shit the pressure becomes so great you hold it in and release pressure, then repeat for the next movement of pressure until the shit baby is born.
1: A self celebration one has on a toilet while defecating after an extremely large satisfying meal. Usually occurs after a large order of fast food. (ie chicken wings).
2: A shit that feels so good it demands instant celebration, or is a celebration in itself.
Examples:
1: After the intense wing eating competition was over, I proceeded to the bathroom and held a shitebration.
2: He walked to the bathroom, boombox in hand, prepared for a shitebration after the long successful dinner.
3: His face showed shear delightment after returning from the bathroom, clearly he just had a shitebration.