When a dog wants to play with you, it will wag its tail at you, turn its belly, bite your trouser legs, etc. When a dog wants to play with you, it will keep wagging its tail in front of you to show goodwill; and the dog’s belly is a very sensitive part. If the dog turns its belly in front of you, it means that the dog wants to play with you. And it trusts you very much; biting your trouser legs is the most direct way to play with you. The dog will come to you, scratch or bite your trouser legs to attract your attention.

Tip:

When the owner is busy, the dog will run in front of the owner and lie on the ground staring at the owner. This is because the dog wants to Playing with the owner but afraid of disturbing the owner, the owner can pet its head or play with it for a while.