I haven't seen an ad offering sign language but my guess is that it's a handjob if you saw it in a body rub or massage ad.
I tried Googling this to no avail... I've seen several ads offering sign language for the hearing-impaired. This is not on the acronym list... hand job?
A variation of it us used to signify a BJ. Is this the info you're seeking?
Are you talking about ASL? I don't know for sure but I don't think there is anythingi established for the hearing impaired in this industry. I could be wrong.
Many years ago I lived with a woman who was slightly hearing impaired. Most of her other friends were more severely hearing impaired. Trust me, they have their own signs for anything and everything intimate!
D.
I haven't seen an ad offering sign language but my guess is that it's a handjob if you saw it in a body rub or massage ad.
It is in the list of options on p411 and this is how it's defined;
"Sign Language
Provider can speak in sign language (for the hearing impaired)."
Doesn't seem like anything sexual is meant by it. Just a straight forward kinda thing. 
xo