Cap, meaning fake or lies. No Facts, of course meaning no information.
This means that the person stating “all cap no facts” is saying you are lying, or being fake.
When you're engaged in an online conversation with someone, but they're extremely stubborn, believes lies or misinformation so you basically have to yell the truth at them so that they would wake up, pay attention and get the point.
Okay Mary, I know you think everything's fine but I need to hit you with an No-Cap All-Cap: YOUR BOYFRIEND'S CHEATING ON YOU AND THE WHOLE NEIGHBORHOOD HAS SEEN IT!!
Means real talk or no lie all facts. Just a quick way of being real. Populated by streamers and tik tokers such as; yamcha the great, jm, thefyp, dani chon, et al.