Disclaimer: I

muffins.
And asparagus.
Derpy Hooves is ableist and Ditzy Doo is sexist. We'd call her Little Miss No Name but Celestia help us we won't want to be seen as dehumanizing her (or poor orphaned dolls). 
Name: Some people use the word 'derpy' as an insult to those who are differently abled.
Eyes: A pony with crossed-eyes who also makes a mistake is ableist.
Mane: A pony with blonde hair who makes a mistake and is unaware of what went wrong is an example of 'Blondes are Dumb' and is sexist.
Species: Describing a Pegasus as 'feather-brained' is racist.
Behaviour: Any pony who acts in a silly or eccentric manner is unintelligent, i.e "Simple minds, simple pleasures"
Status: She's one-dimensional.
Voice: Her voice is un-lady-like.
Cutiemark: Bubbles are full of air which is clearly a reference to her intelligence or lack there off. Her 'bubble butt' reinforces the stereotype that all blonde females are vain, and is also fat-shaming. It will probably promote eating disorders too.

Name: Some people use the word 'derp' to mean a silly unintended but inconsequential mistake, i.e spilling milk. Putting words in their months is offensive.
Eyes: Removing the crossed-eyes is disability erasure and ableist.
Mane: Assuming that anytime a pony with blonde hair makes a mistake, they did it because their hair made them do it is stereotypical.
Species: The idea that it's not possible for a Pegasus to be a 'cloud cockoolander' is stereotypical and racist.
Behaviour: Believing that any behaviour that doesn't conform to the herd is automatically immature and that all immature people are unintelligent is stereotypical.
Status: (As a background pony) she's one-dimensional.
Voice: LOL Mail Pony.
Cutiemark: Oh blow it out your ass.
Conclusion:
I'd write more but I know in my heart that with every word I type it's just one more chance that someone will point out that that word a) has an offensive definition b) will have one in the future and that's
crazy sad stupid odd awkward something.
P.S It's my birthday today. I'm going to celebrate it regardless of how offensive it is to the unborn.
P.P.S Best. Song. Ever.
All ponies must be perfectP.P.P.S

I always say that you can't please everybody but you can offend someone.
That's not a motto or anything, nothings the motto with me.
Edited to add: This here is the journal that I've been waiting to find, that could put into words things better then I can. Cheers. 
Derpygate 2012 - Post Scriptum"Derpy is as derpy does."
~ After Forrest Gump ;P
:icontwilightgalaplz: Greetings, my pretty Ponies! :iconbackhug:
Let me provide some further thoughts and links that I did not include in my first Derpygate article :nod: Click here to listen to Derpy apologizing for being Derpy :cries: If that makes you want to rage, Adolf is your man (that awkward moment when you agree with Hitler). But strong feelings are perfectly understandable, as this video accurately portrays the reaction of the Bronydom about the short life of Canon Derpy. Well, it was fun while it lasted :giggle:
Since I keep reading the same arguments over and over again whereve
I'll quote a small bit of it for you.
""Offensive" is a subjective notion, not a fact. In other words: As soon as a single person disagrees, this claim is refuted. People who shout "This is offensive!" rely on the premise "My opinion is the only truth, and anyone who disagrees is wrong". The mere thought of trying to appease such people seems morally despicable to me. So the next time someone comes up with "This is offensive!", just reply "No, it is not." In the moment where the person admits that it is merely his personal opinion instead of an objective truth, he will have to argue why his opinion should count more than those of the dissenters. I may write a Journal Entry on rhetoric some day where I can go more into depth how to counter various fallacies " THIS. ALL THIS.