1. Get inspired. What do you think would make a fun prop? A moustache? An ice-cream? An envelope with a felt letter? Your fabric stash can be a good place to draw inspiration...do you have some stripes that scream villain or conveniently, a fabric with a ready made prop lurking in the print (see telephone). You could put something noisy inside; crinkly plastic, a bell. The cord can become part of the game too! You guys are the creatives. Go wild.
8. Attach velcro to felt backing and to shirt. Sew a couple of strips of velcro to the back of the felt backing. Cover a generous area...the stuffie needs to be easy to slap on in a hurry (when you have to hang that telephone up fast). Now for the shirt. When considering where to place the complimentary velcro strips see if there is somewhere in the fabric design to disguise black or white velcro, like in stripes as above. This just makes for a slightly neater look but its not a biggie if its not possible. Pin and sew the velcro on, making sure the stuffie has plenty of area to stick to.
Congratulations...if you made it this far you didn't stuff up. Sorry. Now stick it on and enjoy the entertainment.