A popular slogan that Timex used to refer to the impeccable engineering that goes into their watches. While not as snazzy as a pricey dress watch, Timex watches have been shown to withstand lots of punishment and still tell the time. For example, they have even been known to survive a dip in the Dead Sea.
John Cameron Swayze first said the phrase on TV during the 1950s, and would keep using the slogan in the 60s and 70s. The slogan made a brief resurgence in the 1990s with the Timex Turn 'n Pull watch, which was promoted with very retro-looking advertisements. The "lickings" that the watches endured included the spin cycle of a washing machine and the family pet's digestive tract, not to mention being strapped to the outside of an outboard motor. Bernice Kanner mentioned them in his book The 100 Best TV Commercials... And Why They Worked. There isn't a baby boomer alive who doesn't know this slogan; I'm 21 and I still know that it refers to Timex watches.
Also a very silly double entendre, if you're into that sort of thing.
Additional info: http://www.timexpo.com/whatsnew.html