H1: Yo, you hear that new album from some rapper? It's aight, i wouldnt rock it though.
H2: HOMIE, YOU CAPPING BIG TIME H1: Nah, no cap, it's just not for me doe
cap simply is considered as a "lie" or "bullsh!t"
But No cap is a slang that's used by Tiktok 5th grade white boys. It means that something is so true that you have to say a slang or sumthin like what's the point you could simply say tha'ts relatable or its true . It doesn't make people seem cool or up to date it just makes you look like an idiotic white boy.