The process in which a customer or client reduces or "cuts" a salesperson's commission to move forward with the deal. This process is also known as a comissionectomy. It can happen at any point before the salesperson is paid.
Realtor 1: I tried to get 7% for my new listing but the seller would only agree to 6% so I lowered my commission and the house will go on the market tomorrow.
Realtor 2: Looks like she just performed a circumcommission on you tuff guy! How much did you lose?
Realtor 1: Ugh, almost 15%.
Realtor 2: Just like the first time, huh?
Realtor 1: Up yours.