1960s
1960, "dullsville" . . . 1961, "bratty" . . . 1962, "drop-dead gorgeous" . . . 1963, "Mickey Mouse," which meant goofing off at work . . . 1964, "aw shucks" . . . 1965, "grody," which meant gross . . . 1966, "kegger" . . . 1967, "freak flag" . . . 1968, "bippy" . . . 1969, "out of sight."
1970s
1970, "dorky" . . . 1971, "deadheads" . . . 1972, "guilt trip" . . . 1973, "carbo," which is short for carbohydrate . . . 1974, "motorhead" . . . 1975, "detox" . . . 1976, "hardball" . . . 1977, "brewski" . . . 1978, "pig out" . . . 1979, "nostalgia-fest."
1980s
1980, "frizzy" . . . 1981, "chill pill" . . . 1982, "buff" . . . 1983, "beat box" . . . 1984, "that's major" . . . 1985, "radness" . . . 1986, "studmuffin" . . . 1987, "couch surfing" . . . 1988, "F-bomb" . . . 1989, "trash talk."
1990s
1990, "kewl," spelled K-E-W-L . . . 1991, "tighty whiteys" . . . 1992, "NOT," mostly because of "Wayne's World" . . . 1993, "da bomb" . . . 1994, "Benjamins" . . . 1995, "as if" . . . 1996, "whatever" . . . 1997, "jiggy" . . . 1998, "phat," spelled P-H-A-T . . . 1999, "bling."
2000s
2000, "whassup?" . . . 2001, "whale-tail," which is when your thong sticks out . . . 2002, "hella" . . . 2003, "peeps" . . . 2004, "muffin top" . . . 2005, "fo shizzle" and "fo sheezy" . . . and 2006, "sick." As in, "Dude, that shirt is so sick."
(Check out the full list with definitions at GoodHousekeeping.com.)