O.K. You can't really make your dog laugh. But, strangely enough, there is such a thing as a dog laugh. Producing dog laughter correctly can make your dog sit up, wag his tail, approach you from across the room, and even laugh along.
Step 1: The Lips
Round your lips slightly to make a “hhuh” sound. (The sound has to be breathy with no actual voicing, meaning that if you touch your throat while making this sound, you should not feel any vibration.)
Step 2: The Expression
Use an open-mouthed smiling expression to make a “hhah” sound. Again, breathe the sound; do not voice it.
Step 3: Adding Sound
Combine steps one and two to create canine laughter. It should sound like “hhuh-hhah-hhuh-hhah.” Your dog should follow along by sitting up, wagging his tail, approaching you from across the room, or laughing along.