I can do that but I don't wanna
A funny excuse people use when they think they could do something but they don't feel like it. It's like saying you're a boss but you're still too lazy to boss anyone.
'I can do that but I don't wanna' when your friend says they can eat an entire cake in one bite and you're still trying to finish your piece.
'I can do that but I don't wanna' after seeing your dog do a trick and you're still too tired to walk.
'I can do that but I don't wanna' after your teacher says you can take the test tomorrow but you're still going to sleep through it.'