Every cis person is capable of being transphobic. This is just a natural result of growing up in a transphobic society. I've found that in my own life, even well-meaning cis people say things to me that are extremely alienating, often without even realizing it. This fact makes it essential for any cis ally to critically examine their own transphobia and work to dismantle it. I've written before on how to be a trans ally, but I thought it would also be helpful to mention some things to specifically not say to trans people.
1. "Did you have the surgery yet?"
By asking me this question, you are reducing my identity to my genitals. There is also the fact that "the surgery" doesn't really exist as transitioning is a variety of different medical processes. Not to mention, it's an extremely invasive question that you absolutely should not me asking me.
2. "I would have never known!"
I am not valuable because I look cis. My body is a trans body and I am beautiful because of that. When you tell me that you would never have known I was trans and think it's a compliment, you are telling me that you think cis bodies are more valuable than trans ones.
3. "But I'm an ally!"
I don't care how much you think you support the trans community. If you say something transphobic and you get called out for that, you should acknowledge that and do better. Unfortunately, cis "allies" often think their perceived allyship means they know more about transphobia than actual trans people. But we actually experience transphobic, so if a trans person tells you that you are being transphobic, please listen to them.
4. "When did you know?"
Oftentimes, cis people who barely know me think it's okay to ask for my life history. But my journey with my transness was an intensely painful one and it's not something I'm particularly inclined to share with people I don't really know. I'll share my story on my terms, not yours.
5. "You should talk less about trans things."
I carry my transness everywhere I go. It's in my deep voice, my wide shoulders and my "man hands." I talk about trans things not because I want to, but because it's my life.
6. "Transgendered"
I try not to get too caught up in specific terminology, but I physically cringe whenever I hear "transgendered." So please, stop saying it.
7. "What's your real name?"
This particular question is a very common microaggression for trans people. When cis people ask it, they are basically implying that the name a trans person was given at birth is their "real name." But my real name is the name I chose, not the one that was given to me. Plus, I despise my birth name, so I don't really like sharing it.
8. "So are you a boy or a girl?"
This question is often asked by cis people who want to put trans identities in their neat little box of gender. But oftentimes, we exist outside of society's strict binary conception of gender. Forcing trans identities into a neat, cisnormative conception of gender is a very violent act that upholds that system that oppresses trans people in the first place. Plus, once again, this is a very invasive question that you should generally just not ask.
9. "You're so brave!"
Most cis people who say this have good intentions. But usually it comes off as very tokenizing as it reduces trans people to our transness. If you're going to say I'm brave for the things I've done, that's fine. But don't say I'm brave just for being trans.