Your eyes and the turn signal in your car are blinkers.  The Blinker probably has nothing to do with either of them, as the cocktail's origins are unknown.  Patrick Gavin Duffy, a New York City bartender in the late 19th century and pre-Prohibition 20th century, mentioned the Blinker in his 1934 book The Official Mixer's Manual. 75 years later Ted "Dr. Cocktail" Haigh resurrected the Blinker and put his own spin on it.

2 ounces rye (Rittenhouse won't make you blink)
Juice from 1/8 grapefruit 
.25 ounces glorious grenadine or raspberry syrup

Combine in a shaker with ice, be like the Cars and Shake It Up (1980s music fans like me get it), and strain into a chilled glass.  Lemon peel garnish optional.

The sweetener is the real variable.  The original Blinker uses grenadine, and Haigh's version uses raspberry syrup. I tried the Blinker both ways, and I preferred it with grenadine.  It's simply a matter of taste.  If you want to make your own raspberry syrup, start by making a batch of super simple syrup.  Mash raspberries into the mixture when you remove it from the heat source, then strain the solids out after the mixture cools down. 

The Blinker is a little spicy (because of the rye and grapefruit juice) yet refreshing. The result is very drinkable. If you have too many you'll channel some Blink-182 tunes, forget All The Small Things, and ask What's My Age Again.  If you have one or two you'll channel the Cars tune and let the Good Times Roll.  Blink-182 makes good music, but I grew up with the Cars. Regardless of your taste in rock n'roll, you'll enjoy the Blinker for much longer than a _____ of an eye.