Green’s Dictionary of Slang

1. (UK black) to talk to a girl in the hope of seduction, to ‘chat up’.

2015

410 ‘Kick Down Doors’ 🎵 Like fair enough, if the bitch is buff / But dead tings aren’t have to pattern up.

2. (UK black) to plan, arrange; to inform.

2019		Headie One ‘Both’ 🎵 Paps need a pattern business and a pattern up home.
2021		Central Cee ‘Dun Deal’ 🎵 TB on the phone to the holder, patternin' up 'cause the dough just dropped.