They actually all lie about different things.

Grey cat likes to lie to get into the room you're in, if the door is closed, by pretending there's a horrific emergency on the other side of the door. "Help! Help! Let me into the bathroom with you! My agony shall not subside until I have access to this room! I am ill! I am dying!"

Stripey cat likes to open cupboard doors, cardboard boxes and then hunt, kill and eat pouches of wet cat food, then pretend it wasn't him at all, and he is hungry and hasn't eaten for days.

Black cat likes a more traditional "I've not been fed yet, I am starving", and also "I have no idea how the water bowl ended up upside down, but it looks like we're out of water again".

Thankfully, none of them will scratch or bite (at least not me or my partner). Black and stripey will both gently push your hand away when they've had enough tummy-tickle-time. Grey cat can be tickled for at least ten minutes. He just waits for you to get bored.