Contains mild language

Spotted on a poster at Buxton Community School last night, advertising a student production called Threads: ‘contains mild language’. As the OED definition of mild includes ‘not giving offence to others’, I assume this isn’t the 1984 television drama about nuclear war written by Barry Hines. I wonder if this warning is to prepare an audience hoping for something satisfyingly controversial that they might be shocked by the bandying of terms such as nesh, soft and even nice.
Alas, such thrills were not for me: instead, I enjoyed a two hour presentation on the future for the local authority, the challenge of academies, free schools and the like. Some folk didn’t seem very mild about that, though (to quote Friday’s Phrase) no sabres were rattled.