Lap – The loose lower part of a garment, which may be doubled or folded over; To drink by dipping it up with the tongue in the manner of a dog.
God used this word 7 times in Scripture: every instance is to Israel in the Masoretic Text Old Testament.
God used this word 4 times in the sense of drinking, and 3 times as the lower part of a garment that is folded up and used to carry something or someone.
When you sit in someone’s lap, it is a reference to sitting on the lower part of the front of their garment when they are seated. You cannot sit on their lap when they are standing. But if you are small enough, you can be carried in their lap.