A drinking cup container (12) has a cover (14) which is formed with a drinking spout (22) at one side and a vent (28) at the other. Elements (26, 30) extend down from under the spout and the vent. A flow control element (40) is provided and made of elastomeric material having a pair of spaced cavities (42, 44) on one side, each cavity having a floor (46, 48) at the bottom thereof. The cavities receive in frictional engagement, respectively, the lower ends of the elements. This engagement supports the flow control element with the floor of each cavity in sealed relation to its element. Each floor has a passage (54, 56) which is normally closed, but opens on the occurrence of a pressure differential on opposite sides of the floor.