'The T' is another term for 'the Truth.' The term was popularized in gay culture. 'The T' was brought mainstream by RuPaul's Drag Race, TV, series, as the Drag Queens, and Drag Racers (series viewers) would refer to 'The T' when speaking the Truth.
The T can also refer to getting the scoop or inside information about something.
That queen's skirt is too short. I just had to speak the T.
RuPaul was preaching the T when she said, If you can't love yourself how the hell you gonna love anyone else.
I know he was checking me out. I wouldn't lie. I only tell the T.
Girl, you better tell me the T about what you heard from that bitch.
I'm not running my mouth, but let me drop the T on you.