1) Creating an advertisement for sportswear
Advertisements usually don't need to be written in a formal way, as for its purpose is to attract prospective buyers' interest to buy a good or service. These potential customer, especially of sportswear, are usually average people that may identify better with words that are common and relatable to them. This is why using colloquial words, slang, first-person pronouns and an every-day vocabulary in an advertisement for sportswear is more likely to attract people's interest and sell more than when informal English is used.