A deaf participant in auctions developed a system
with his hearing friend.

The hearing person would tap the deaf person on the
shoulder to tell him that the item he wanted was
now ready for bids.

Each tap would tell deaf person to bid higher.

A cut-throat sign by the hearing person would
tell the deaf person that his bid limit was
reached and to stop bidding.

It worked as the deaf person was able to bid
for stuff he wanted.