you get a voucher each time you win the hot dog eating contest, you're supposed to hand those to your colleagues
I have been I got 3 vouchers and gave them to green, blue and tried the office witch but she refused so I gave the it to pink instead. I constantly checked on the vendor for each size level since one commenter said the contests stop if you get "too big" so I know I didn't miss any unless there are more than 3 contests.