Bartenders are not being fussy when they insist on the double-pour. Unlike other taps, Guinness is dispensed through a five-hole disk restrictor plate. It supplies an uncommon amount of nitrogen, making the head extra-effervescent. As such, two shifts are needed: one to start the magic, and a second to finish the job. The perfect pint is said to take 119.5 seconds to pour. But who’s counting?