48 CFR 31.205-14: 31.205-14 Entertainment costs.

Costs of amusement, diversions, social activities, and any directly associated costs such as tickets to shows or sports events, meals, lodging, rentals, transportation, and gratuities are unallowable. Costs made specifically unallowable under this cost principle are not allowable under any other cost principle. Costs of membership in social, dining, or country clubs or other organizations having the same purposes are also unallowable, regardless of whether the cost is reported as taxable income to the employees.