In their commercials promoting a special type of athletic gear that supposedly improves performance, SKINS uses the phrase “Cheat Legal“. One of the videos can be watched here. The word “legal” in this phrase can either be an adverb characterizing the verb “cheat” (in which case it should be replaced by the grammatically correct form “legally”), or an adjective. In the second case, the use of “legal” rather than “legally” is acceptable, although “Cheat Legal” does not exactly represent a complete English sentence since there is no noun. The expression is similar to phrases such as “Forget healthy” or “Ignore dangerous”.