As long as they say some variant of 'keep calm and carry on' on the front, that's fine.
(
The Porcupine From Purgatory katsu revival trust,
Wed 26 May 2021, 16:00,
archived)
Keep calm and let the 80 year olds pile high
(
dribble,
Wed 26 May 2021, 16:16,
archived)