Dobie and Maynard
That’s quite a bit of work for a slacker duo.
I’m going Dante and Randall…the most work they ever did was climbing on the roof for the hockey game.
Brodie Bruce and T.S. Quint. Mallrats. All they did was walk around the mall.
Put in another one for Dante and Randall as well.
Adam and Eve
Leading by example – excellent! 
Harpo and Chico Marx
Some obscure ones:
Jim Kane and Leonard - Pocket Money
Jack McKee and Cecil Colson - Rancho Deluxe
Trinity and Bambino - the Trinity films. One is too lazy to even ride his own horse, and both are never happier than while eating an enormous plate of beans.
I like the thought of Harpo and Chico as slackers. They’d be the OS when it comes to film, I guess.
Kit (Martin Sheen) and Holly (Sissy Spacek) in “Badlands”.
Manny (Scarlett Johnasson) and Lo (Aleksa Palladino) in “Manny and Lo”.
Harold and Maude
Abbott and Costello
Patsy & Enid (AbFab)
and I can’t believe no one mentioned…
LENNY AND SQUIGGY
Harpo’s too busy running around to qualify as a slacker, ainnhe?
Chico, though, no problems.
My massive testicles.
No, seriously! All they do is hang around!
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Dante is specifically disqualified. He showed up to work when he “wasn’t suppose to be here today!”
I have to second a few:
Jay and Silent Bob
the Dude and Walter
Lenny and Squiggy
Patsy and Edina
Dante and Randall
Jesse and Chester
Arthur Dent and Ford Prefect
G-Unit and his bumbling sidekick WillSantini.
Harpo is usually up to no good, messing with people (chasing girls or irritating the squares and stuffed shirts), or off in his own little dream world (for example: off playing a harp instead of doing what he was supposed to be doing). Not to mention he’s rarely gainfully employed (or will soon be fired if he is), is often a stowaway, mooches food, gate crashes constantly, sleeps at the drop of a hat, filches silverware and anything else he can get in his coat, and takes part in Chico’s plans and schemes.
Sounds like a slacker to me.
Richard Richard and Eddy Hitler (Bottom)