Playing games with food as part of oral sex is a great prelude to eating cum, since it gets you habituated to associating sucking cock with swallowing something that tastes good. And you can easily use a mouthful of chocolate syrup or honey to chase down the cum and get the taste out of your mouth. Using whipped cream from an aerosol canister is perfect. Once he cums, immediately stick the whipped cream nozzle in your mouth and spray; you won't be able to tell the cum from the cream.