Abstract: A twist-on/twist-off dispenser cap, of a type normally used for dispensing mustard or ketchup, comprises a bottom cap portion which screws onto a cooperating container and a generally cone-shaped spout portion which is captively held by a screw-type arrangement on the bottom cap portion. Rotation of the spout portion with respect to the bottom cap portion allows an orifice at the tip of the spout portion to be either opened or closed. A relatively wide annular flange at the base of the spout portion fits into a corresponding shallow recess in the top of the bottom portion of the dispenser cap. The flange and a plurality of spaced circumferential ridges at the periphery of the flange allow excellent gripping of a shrink-wrap seal to make the dispenser cap tamper-proof. The container onto which the dispensing cap is screwed has a circumferential collar adjacent a threaded neck portion. Two series of notches on opposing sides of the collar define intervening protuberances.