I heard the question: "What are you talking about?" frequently in American movies. However I notice they tend to drop the verb "are" and treat "y" as a vowel. The /t/ in the word "what" sounds like a flap t (tapped T). I'm not a native speaker and I'm trying to rely on my ears. I would like to know if my observation is correct. I would be grateful for any suggestion.
I think this is the pronunciation that is sometimes written "What'cha talking about?" or "Whaddaya talking about?" (depending on the speaker's accent).
If so, I think that most native speakers would consider the verb to still be there even though it has been almost completely swallowed. If you ask someone to repeat the question slowly they will likely either produce the verb ("What ... are ... you ..."), or keep it combined with the "what" ("Whadda ... ya ... talking ... about?"). But that could vary by dialect.