According to CNN Traveler, "To drink like a [Venetian], walk into a neighbourhood bar and ask for a spritz, the archetypal Venetian aperitivo, concocted from white wine, Campari and soda water. The spritz is one of the cheapest and quickest routes to alcoholic oblivion known to man; you'll be under the table after three. The classic spritz al bitter (with Campari) has two more recherché variations, the spritz al Aperol (tastes like medicine) and the spritz al Select (tastes like sweet medicine)."
The Campari spritz will really put hair on your chest... so my favorite instead is the Spritz al Aperol, which (contrary to the above!) actually goes mighty fine with an olive and an orange slice! (Oh, here's an Aperol commercial, for your enjoyment!) BTW, in a culture which drinks like fishes but doesn't approve of getting stinking drunk, needless to say, I've never seen Venetians pound down three of these in rapid succession... They just drink them during "Spritz Hour," which runs only from about 10 am and to just before dinnertime!
Now, despite the fact that this excellent article doesn't really mention it, the Spritz is yet another fine contribution of Venice to world civilization!
Local Venetian legend has it that when the Austrians took possession of Venice during the nineteenth century, they found the local wine too strong for their tastes, and so they'd ask for it to be diluted with a spritz of soda water. Venetians thought this was a good idea, but found it way too weak for their tastes, so they turned back around and re-fortified it with a good half-glass of aperitif liquor, ranging anywhere from 24 to 50 proof! (This from the same people who can add a shot of grappa to their morning espresso and call it a "corrected coffee," otherwise known in Venetian as a "fog-cutter"...)
For more wonderful words on the Spritz, see the great Veniceblog, the official Spritz.it from nearby Padua, and (very strangely... I don't really get it...) another blog on drinking and/or driving in the news by an Italian alcoholism treatment counsellor... (And below, "Spritz Hour" in the university quarter of town!)
However, while it would be near taboo to suggest such a thing in Venice, you can attempt to make a "virgin" spritz with sparkling or soda water and the non-alcoholic "Gingerino" or "Sanbitter"...