So let’s see:
Cats
Liberalism, and all that implies (pro-life, pro-choice, etc)
Saying things like “kerfluffle” and “squee”
Inserting Hitler references into as many threads as possible
Goats
What else?
Sex
The Simpsons, with encyclopedic recollection of quotations
The Princess Bride
Monty Python
Blazing Saddles
Airplane!
To answer this question perhaps more seriously than it deserves, there’s obviously nothing that ALL dopers agree on, aside from vacuous or trivial observations (I hope that gravity doesn’t cease to work tomorrow).
But if you’re looking for a position where the opinion on the dope is nearly universal, while opinion in the outside world is not, I’d say, even more than opposition to Donald Trump, the most agreed on topic on the dope is support for Gay Marriage.
Universal Health Care is actually a good thing.
+Dogs/Pets of all sorts and their pictures
Well, not all of us and not all the same way. This is a good thing.
I thought this was frowned upon…
Squid
[del]heated arguments and pedantry[/del] Discussions and debate
You know who else frowned upon it?
Exactly.
Definitely NOT cats!
shakes fist curse you, foiled again! 
… and treadmills.
Colonoscopies.
I did a poll one time: Who do you think is better? Bugs Bunny or Mickey Mouse? The results were unanimously in favor of Bugs Bunny.
That doesn’t surprise me. Bugs is WAY funnier than Mickey, and plus to not having the annoying high-pitched voice, NOR having to deal with Minnie Mouse.
Best Bugs: “Nighty, night, rabbit…”
“Nighty…night…”
…floats away from castle on mattress…
Throwing things into quarries.
Bacon
With or without paper towel tubes?
The ability to discuss things using more than 140 characters which is a severe limitation of other Internet communication tools such as twit
er
Good point though. One thing I am certainly fond of about the Dope is that most of us are more eloquent than the average internet bear. It’s nice to be able to visit a website and share opinions and comments without the cringe-worthy aspects of the comment sections of other websites.
1920’s style death rays seem to be a big hit.