Show it to a test audience, and record their responses during the show and their answers to questions about it afterward.
15
Varsity Show - 1937 is rated/received certificates of: Australia:PG Australia:G (TV rating) Finland:S USA:Approved (PCA #3393) USA:TV-G (TV rating)
Home and Away - 1988 is rated/received certificates of: Australia:PG (TV & DVD rating) Australia:G (TV rating) Ireland:12 Netherlands:6 New Zealand:PG (TV & DVD rating) New Zealand:G (TV rating) UK:12
Maiden Voyage - 2004 TV is rated/received certificates of: New Zealand:PG (TV rating) New Zealand:PG (cable rating) UK:15 USA:R
The Ridiculously Awesome Show - 2009 TV is rated/received certificates of: USA:TV-14 (TV rating)
Side Show - 1931 is rated/received certificates of: USA:TV-G (TV rating)
Show Boat - 1929 is rated/received certificates of: USA:TV-G (TV rating)
The Chris Tabb Show - 2011 is rated/received certificates of: USA:PG (TV rating)
All 236 episodes of Friends have a ceritficate rating of 12 apart from the whole of Series 5 which is given a certificate rating of 15.
An audience rating is approval or disapproval by an audience. Often, TV shows and movies are screened before an audience to see how the show or movie will do when released to the public.
The Show - 1927 is rated/received certificates of: USA:Passed (National Board of Review) USA:TV-14 (TV rating)
It has very inappropriate language. I am not exactly sure that the grossness in the show affects its TV rating.