It's about nine-tenths as heavy as a Deck of Cards
In other words, 80 grams is 0.85 times the weight of a Deck of Cards, and the weight of a Deck of Cards is 1.2 times that amount.(ISO 216 B8 size, a.k.a. "poker size" 63 x 88 mm, 52-card deck)
A deck of 52 ISO 216 B8-size playing cards weighs 94 g. Utilizing nearly 3,700 decks, the record-holding largest card tower was built in early 2010, stood over 3.5 m (11 ft), and weighed over 230,000 grams.
It's about one-and-one-fifth times as heavy as a Battery (C)
In other words, 80 grams is 1.2 times the weight of a Battery (C), and the weight of a Battery (C) is 0.83 times that amount.(Alkaline)
A "C" size battery weighs 65 g. C batteries are typically used in medium-drain devices such as musical instruments.
It's about one-and-two-fifths times as heavy as a Tennis Ball
In other words, 80 grams is 1.39 times the weight of a Tennis Ball, and the weight of a Tennis Ball is 0.719 times that amount.(ITF Standard; for Type 2 ball)
Per International Tennis Federation standard, regulation tennis balls must weigh about 56.0 g to 59.4 g. Competition balls are also tested for bounce height, with the standards requiring that a ball dropped from 254 cm must bounce back to a height of 135 cm to 147 cm.
It's about three-fifths as heavy as a Battery (D)
In other words, 80 grams is 0.593 times the weight of a Battery (D), and the weight of a Battery (D) is 1.69 times that amount.(Alkaline)
A "D" size battery weighs 135 g. The D size battery is the oldest of the modern battery sizes, first invented by the National Carbon Company in 1898.
It's about one-and-three-fourths times as heavy as a Golf Ball
In other words, 80 grams is 1.742 times the weight of a Golf Ball, and the weight of a Golf Ball is 0.5741 times that amount.(per R&A USGA Rules of Golf; maximum rule weight)
According to the Rules of Golf (as approved by the United States Golf Association and the Rules Committee of the Royal and Ancient Golf Club of Saint Andrews), golf balls must weigh no more than 45.93 g. Golf balls are not required to have the familiar dimpled pattern, but the design has been popular since its invention in 1905 because it reduces drag while increasing lift.
It's about three-fifths as heavy as a Baseball
In other words, 80 grams is 0.5506179426276 times the weight of a Baseball, and the weight of a Baseball is 1.8161413251953 times that amount.(MLB rules)
Per Major League Baseball rules, a baseball must weigh between 141.747615625 g and 148.83499640625 g. A major league pitcher can throw a baseball at up to 150 kph (91 mph) (with a fastball pitch), with record-setting pitches as fast as 171 kph (106 mph).
It's about half as heavy as a Billiard Ball
In other words, 80 grams is 0.49076816625503 times the weight of a Billiard Ball, and the weight of a Billiard Ball is 2.037621974609 times that amount.(American-style, WPA specifications)
Per the World Pool-Billiard Association, a billiard ball weight must weigh between 155.9223771875 g and 170.09713875 g. According to legend, the difficulty in obtaining elephant ivory for the manufacture of billiard balls in the 19th century inspired the search for a replacement material, which led to the development of the first industrial plastic.