Fart sounds

My daughter is wonderful.  Yesterday she was unhappy about something, so I stuck my tongue out at her and made a fart sound (I don't recommend this for dealing with unhappy women over the age of 3, however).  She immediately smiled, so I did it again and again, and she became more and more excited and giggly each time.  Finally, she decided she wanted in on the fun, and stuck her tongue out.  She crossed her eyes and fixed them on the tip of her tongue and looked expectantly at it, waiting for the sound.  She starting straining her neck forward, trying to figure out why her tongue wouldn't make a noise.  When she surmised that that wouldn't work, she tried darting her tongue in and out like a little frog.  Still nothing, so she decided it wasn't going to happen for her and reverted her attention to my tongue farts, a big grin on her face.