Can one give a present on shabbas? If the answer is no, then how does it work when one eats by someones house the food one gets is a present (it is changing reshus). Sources please.
Are coupons for items which are chometz, chometz themselves? Do they have a status of chometz, or can they be dealt with on Pesach? For example: Can one acquire coupons for grain cereals on Pesach ...