The code word used by many walgreen's clerks far and wide, over the intercom to let a fellow co-worker know that there are more than 3 customers waiting in line. When "IC3" is called over the intercom, a co-worker will take some of the waiting customers at a seperate register, hence improving customer service.
IC3 = I SEE 3 (customers)
(4 customers waiting in line)
Cashier1: (over the intercom) "IC3"
Cashier2: (to customers) i can take some of you at cosmetics.
-customer service is boosted
KNOW YOUR SHIT.