Tottenham Hotspur have become the first football club to feature the slogan "not all disabilities are visible" on their disabled toilets.
Some supermarkets are doing it too.
It's all part of a move to try and recognise people with invisible illnesses - disabilities and long-term health conditions that aren't physically obvious.
Many of them fear confrontation because they feel they don't fit the image of a disabled person.
Two long-term sufferers of health conditions explain why the new signs are needed:
Mel Richards, 23, suffers from Multiple Sclerosis (MS).
"I think the main thing you need to remember is MS symptoms are different for every sufferer - for me it's the invisible symptoms of fatigue, loss of sensation in your limbs and fingertips and large amount of pain that's difficult.