A mutual agreement, of which, the effects, with respect both to the advantages and losses, whether to all the parties or to some of them, depend on an uncertain event. Civil Code La. art. 2982; Moore v. Johnston, 8 La. Ann. 488; Losecco v. Gregory, 108 La. 648, 32 South. 985. A contract, the obligation and performance of which, depend upon an uncertain event, such as insurance, engagements to pay annuities, and the like. A contract is aleatory or hazardous when the performance of that which is one of its objects depends on an uncertain event. It is certain when the thing to be done is supposed to depend on the will of the party, or when in the usual course of events it must happen In the manner stipulated. Civil Code La. art. 1776.