Suitable for 18 years or older. This is real life. Anything in this category is considered to be of subject matter relating to adult life, that happens day in and day out. Walking down the street is an 18 certificate. You have a life, well done.
Examples: American Beauty, Scary Movie
To quote the BBFC: The R18 category is a special and legally restricted classification primarily for explicit videos of consenting sex between adults. Such videos may be supplied to adults only in licensed sex shops, of which there are currently about 90 in the UK.
You are filthy. Congratulations!
Not entirely sure why considering my sex life is tame as f*** but I guess all the booze, swearing and drugs doesn't help my rating