E.H.
Give it to him in the bath. Not bath water, but juice or milk (not water so he thinks he can use bath water) You have to watch that they are drinking and not playing and talk about not drinking bath water, but let him "play" with his tounge at first. Putting his tounge in is just experimenting because there is no lid. This is normal and will pass, so a few bath time drinks and it should be over. I also gave them water outside to practice. So if it spilt no big deal. Small cups to start are a good way like little dixie cups.