Passive smoking is the inhalation of smoke, called second-hand smoke (SHS), or environmental tobacco smoke (ETS), by persons other than the intended 'active' smoker. It occurs when tobacco smoke permeates any environment, causing its inhalation by people within that environment. Exposure to second-hand tobacco smoke causes disease, disability, and death. The health risks of second-hand smoke are a matter of scientific consensus. These risks have been a major motivation for smoke-free laws in workplaces and indoor public places, including restaurants, bars and night clubs, as well as some open public spaces.

Concerns around second-hand smoke have played a central role in the debate over the harms and regulation of tobacco products. Since the early 1970s, the tobacco industry has viewed public concern over second-hand smoke as a serious threat to its business interests. Harm to bystanders was perceived as a motivator for stricter regulation of tobacco products. Despite the industry's awareness of the harms of second-hand smoke as early as the 1980s, the tobacco industry coordinated a scientific controversy with the aim of forestalling regulation of their products.

A second-hand or used good is one that is being purchased by or otherwise transferred to a second or later end user. A used good can also simply mean it is no longer in the same condition as it was when it was first transferred to the current end user. Used goods may be transferred informally between friends and family for free as "hand-me-downs" or they may be sold for a fraction of their original price at garage sales or in church bazaar fundraisers. Governments require some used goods to be sold through regulated markets, as in the case of items which have safety and legal issues, such as used firearms or cars; for these items, government licensing bodies require certification and registration of the sale, to prevent the sale of stolen, unregistered, or unsafe goods. As well, for some high-value used goods, such as cars and motorcycles, governments regulate used sales to ensure that the government gets its sales tax revenue from the sale.

Second-hand goods can benefit the purchaser as the price paid is lower than the same items bought new. If the reduction in price more than compensates for the possibly shorter remaining lifetime, lack of warranty, and so on, there is a net benefit.

Penn & Teller (Penn Jillette and Teller) are American illusionists and entertainers who have performed together since the late 1970s, and are known for their numerous stage and television shows. Their current Las Vegas show is an amalgam of illusion and comedy. Penn Jillette is a raconteur; Teller generally does not speak while performing, although his voice can occasionally be heard during their performance. They specialize in gory tricks, exposing frauds, and performing clever pranks. More recently they have become associated with atheism, scientific skepticism, and libertarianism, particularly through their television show Penn & Teller: Bullshit!.

Penn Jillette and Teller were introduced to one another by Weir Chrisimer, and they performed their first show together at the Minnesota Renaissance Festival on 19 August 1975. From the late 1970s through 1981, Penn, Teller, and Chrisimer performed as a trio called "The Asparagus Valley Cultural Society" which played in San Francisco at the Phoenix Theater. This act was sillier and less "edgy" than today's Penn & Teller act.^{[citation needed]} Chrisimer helped to develop some bits that continued, most notably Teller's "Shadows" trick, which involves a single red rose.

John Rodney Mullen (born 17 August 1966) is a professional skateboarder who practices the disciplines of freestyle and street skateboarding. Mullen is credited with inventing numerous skateboarding tricks, including the kickflip, the heelflip, the impossible and the 360 flip. Mullen has appeared in a large volume of skateboarding videos and has co-authored an autobiography entitled The Mutt: How to Skateboard and Not Kill Yourself with Sean Mortimer (Mortimer also co-authored a Tony Hawk autobiography).

In a 2009 video Mullen sums up his passion for skateboarding:

I fell in love with skateboarding because it was individual. There were no teams, there were no captains... it was completely opposite of what I saw in so many sports: It was creative.

Mullen was born in Gainesville, Florida, United States (US), and began skateboarding at the age of ten after a neighbourhood friend introduced him to a skateboard. He promised his worried father, a dentist, that he would cease skateboarding the first time he became seriously injured. Mullen began practicing whilst wearing a complete pad setup, as part of the deal with his father, and spent time with his sister's surfer friends, who skateboarded on weekdays. Mullen subsequently became obsessed with the skateboard and practiced for many hours on a daily basis.