Trainer straw cup

<p>I brought my 20month old son a straw cup and I didn't mind the price because I heard Munchkin is nice. It is the last time I will buy a Munchkin product! He keeps on complaining that the water isn't coming out, when I tried, I had to suck until my breath was finished before I got a small sip. How must a baby use a "baby product" that adults struggle with? </p>