I ain't went this hard since I was 18
Drake hasn’t gone this hard in his rap career since he was 18. Drake released his first mixtape, Room For Improvement in 2006 (5 years ago), and he is now 24. He was around 19 years old when his first mixtape came out, so this is probably a reference to his early work.
He’s also implying that when you are young you party hard. Young people usually have fun and do things older people don’t do. So he’s partying like he did when he was younger.
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