The term 'BUT' is a three-letter word that is used as a conjunction to introduce a phrase or clause that contrasts with or reverses the previous statement. It is often used to express surprise, disbelief, or disagreement. In this context, it is used to emphasize the importance of the following statement, which is 'Seriously Folks...'. This phrase is used to indicate that the speaker is being serious and sincere in their statement, and that they expect the same level of seriousness from their audience.