2 CFR §200.438

1. (a)Entertainment costs. Costs of entertainment, including amusement, diversion, and social activities and any associated costs (such as gifts), are unallowable unless they have a specific and direct programmatic purpose and are included in a Federal award.
2. (b)Prizes. Costs of prizes or challenges are allowable if they have a specific and direct programmatic purpose and are included in the Federal award. Federal agencies should refer to OMB guidance in M-10-11 “Guidance on the Use of Challenges and Prizes to Promote Open Government,” issued March 8, 2010, or its successor.