Someone in a pink shirt is riding a brown horse in a rodeo.
The cowboy is in competition at the rodeo.
Someone in a pink shirt doesn't have to be a cowboy just because they are riding a brown horse in a rodeo. They could be a wrangler or a barrel racer, or even a carney. "In a rodeo" doesn't imply being "in competition" either. The person riding the brown horse could be an entertainer or wrangler.
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