Bubble wrap , wrapping paper, my Rex loves the cracking sound when she walks on it and will need it like a cat.
She and Toothless also like the sound of the metal floor cross tube on a camp stool, will climb over it and go back for more several times in succession.
Puff loved to nudge his dome light fitting (had a 13W UVB200 in it and was hung pendulum style) , he'd repedatively nudge it with his nose or reach up and pat it with a hand and make it swing and would do this for ages in his tank.
My observations are my skinks (especially water skinks) and my beardies have a definite sense of fun and are capable of inventing games all by themselves.