Somewhat bad taste I'm afraid (and another repeat, I'm sure)
A young man got a job as a barman'waiter in a large pub that was used regularly by the patients of a clinic for hearing and speech-impaired next door
The guv'nor carefully taught him the signing for all the drinks he was likely to be asked for and the young man seemed to take up the tast easily
He went through his first day without making a single mistake until closing time when the guv'not told him to call time
He walked into the br where he found it crowded with people, totally silent but all swinging their hands up to shoulder height in pefect rhythm
Puzzled, he went into the lounge to find exactly the same thing taking place
He sought out his boss and told him what was happening
"Shit - we'll never get them home now they've started to sing"
Jim