The Federal age of majority in Canada. You can vote in federal elections, and in most provinces you can buy porn, have sex with grown-ups, have anal sex. (not that there's a big anal sex law enforcement agency or anything..) In some provinces, notably Quebec, Alberta, and I think one or two others, 18 is also the provincial age of majority, which grants the ability to vote in provincial and municipal elections, buy and drink alcohol and tobacco products, and be considered a legal guardian, among other more arcane rights.