"What are we doing here?" (All the time, about everything. It's his version of "Why is the sky blue?")
"Don't sing." (In a dead-serious tone of voice to me in the car, every time I unconsciously begin to hum along to the radio.)
"No thank you!" (His version of "no". It's like he thinks we have to go along because he's saying thank you. You would think it would be more polite when phrased that way, but it's not-so-much.)
"Would you like to [fill-in-the-blank]?" (Translation, "I would like to [fill-in-the-blank]." And the blank is often filled with "go get some ice cream".)
"Can I give you kisses?" (When he doesn't want to go to sleep at night. Because he knows the answer to that question is always, "Yes!")
"Can we snuddle?" (Same.)
Additionally, when I picked him up from school one day last week, he perfectly sat on the potty, peed, flushed, and washed his hands, all without a bit of help. He probably shouldn't have shown me he can do that.
Also, he sleeps with cars. Every night at bedtime, I ask, "Do you want Jamie [his doll] or Eddie [his bunny]?"
"No, can I pick out a car?"
I don't understand it as comfort object, but it seems to be his thing.