This is not a punishment pic. Sweetie got herself into this, long story short: 
Rarity has this machine hidden in the basement. One day when Rarity wasn’t home Sweetie Belle sneaked inside the basement.
 
Sweetie Belle thought this was a massage table , she sat down and sat what she thought was a timer to 15.  
The machine started on, strapped her in and started spanking her hard. The dial was in fact the force of the spanks and she put it on max.
 
She couldn’t reach the controls due to her short limbs. Cause this machine wasn’t meant for little fillies she got stuck there crying and bawling being spanked till Rarity came back home.
 
Read the full fanfic here