To be sincere about giving s.t. to s.o. (This is also one way that Mapun people say thanks to s.o. when they are given s.t.).
Be sincere, okay, concerning those bananas that you gave me? (Mapun way of saying thanks for giving me those bananas).
I haven't sincerely given up my money that they stole. (Mapun way of saying one still has hard feelings about being stolen from).