Initiate interaction with playful banter.
Child will probably counter-act with feigned sleepiness. The proper response: enjoy a brief moment of snuggles.
Making faces is a good way to entertain.
If all else fails, tickling will result in joyful laughter and plenty of squirming and wiggling. This will tire the child to a point of exhaustion, should you stick with the tickling long enough.
Congratulation! You have successfully worn out your child. Now finish browsing facebook in peace.
And Witten's all like, "Yeah, Whatever"