The ad must come down by Thursday, though, due to Rule 40 of the Olympic Charter, which is detailed here. The rule prohibits Olympians from promoting non-official Olympic sponsors during and around the Games.
The rule reads: "Except as permitted by the IOC Executive Board, no competitor, coach, trainer or official who participates in the Olympic Games may allow his person, name, picture or sports performances to be used for advertising purposes during the Olympic Games."
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A blackout period runs from Jan. 30-Feb. 26.
Rule 40 does allow exceptions, waivers granted by the U.S. Olympic Committee, but they are usually reserved for USOC sponsors. Guinness is not a USOC sponsor.
Olympians should be aware of this rule. It appears many are: