Can't nobody do it like you do it, like you do it, like you do it, like you
I can't imagine myself without you
I need a whole lot of help without you
Me and my granny both agreed
Damn you're such a G I’ll hold you down forever, B

from Big Sean (Ft. Miguel) – Ashley Lyrics on Rap Genius

Meaning

Sean expresses his love for Ashley. He reiterates that she is the perfect girl for him, and he can’t live without her, a common sentiment among lovers. Ashley was an important source of moral support for him, and he wouldn’t be able to get through the day without her. She also had the approval of Sean’s grandmother, who was another important woman in his life.
Sean signs off calling Ashley a ‘G’, a term of endearment usually reserved for one’s closest friends, so you know how much he appreciates her.

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