An adage used as a psychological tool to expose bias.
The key portion is the last word, which used in this context can be interpreted either as a statement of truth (i.e. oranges are orange) or as a pejorative insult (Those shoes are gay). Essentially it
will trigger
people who are easily triggered. The point of doing this is to
show that an inherently unbiased statement is interpreted by the individual to follow their own rationale, often
time exposing their bias towards negative interpretation.
Similar to "It's okay to be white".