In a gesture of absolute acceptance of Spin as a new friend Luffy both offers him a piece of meat from his packed lunch which he aggravated Sanji into making in a bid to keep him out of the kitchen and enquires as to whether he has made any plans for the future.

He chooses to phrase it like this;

"Wou't foo ueik sc'om?" [trans; would you like some?]
"Oo're fun, *swallows* wanna join my pirate crew? I'm gonna ask Mr Brook too!"