Brouwerij Bosteels (Bosteels Brewery) is a brewery in Buggenhout, Belgium founded in 1791 owned and operated by the same family for seven generations until its sale in 2016. They brew three beers: Tripel Karmeliet, DeuS, and Pauwel Kwak.
According to their website, at the turn of the 19th century Pauwel Kwak was a brewer and the owner of the De Hoorn inn (near Brussels). Mail coaches stopped there every day, but at that time coachmen were not allowed to leave their coach and horses. As a result, the inventive innkeeper had a special Kwak glass blown that could be hung on the coach. In this way, the coachman had his Kwak beer safely at hand.