Let's say my opponent has a Crackleburr, two red and blue useless tokens, and an infinite amount of red and blue mana. Crackleburr's card text is this:
{U/R}{U/R}{T}, Tap two untapped red creatures you control: Crackleburr deals >3 damage to target creature or player.
{U/R}{U/R}{Q}, Untap two tapped blue creatures you control: Return target creature to its owner's hand.
Now let's say that my opponent, on his turn, activates Crackleburr's first ability to kill a creature of mine. I respond with Path to Exile on Crackleburr. Can Crackleburr respond to that Path to Exile by activating his second ability? Then, assuming it can, can Crackleburr respond to his second activation by activating his first ability again? So, with infinite mana, can Crackleburr continually respond to itself?