66 (German Sechsundsechzig, also called Paderbörnern) is a fast trick game with 24 cards for 2–4 players. It belongs to the "marriage" family, where king and queen of the same suit score a bonus. In Germany 66 is about as well known as Skat, and the Austrian 20-card Schnapsen is a close relative. It is an old folk game with no owner.
Sources: Sixty-six · Pagat – Sechsundsechzig