TONGUE TWISTERS:

1.George Gabs grabs crabs.
Crabs George Gabs grabs. - I'm not sure what you mean by this. You could say something like: "Crabs are what George Gabs grabs", but that's not as challenging to say.

When George Gabs grabs crabs,
how does George Gabs grab crabs?

2.Luke Luck likes lakes.
Luke's duck likes lakes.
Luke Luck licks lakes.
Luck's duck, Duck, licks lakes. - I just named the duck 'Duck' so you don't need to use 'the' in the next two lines.
Duck takes licks in lakes Luke Luck likes.
Luke Luck takes licks in lakes Duck likes. - "...take licks" sounds awkward, but the meaning is clear and the sound fits the poetry.