From the Super Mario Wiki
In The Super Mario Bros. Super Show! episode "Toad Warriors", King Koopa, attacking on a Rebel Fort in Car Land, called for Thunder Birdo to use in the attack. Hearing King Koopa, Mouser rushed to get Thunder Birdo, who he brought forward on a car.
Once in position, Thunder Birdo fired a giant egg at the Rebel Fort, which exploded violently upon the building, heavily damaging it. After this first attack on the Rebel Fort, the Thunder Birdo continued blasting the building with more of her explosive eggs.
Later, after Mario and Princess Toadstool had driven away from the semi-demolished Rebel Fort in a spaghetti sauce tanker truck, Thunder Birdo, riding a car driven by Mouser, tried attacking them. Before Thunder Birdo could fire an egg at Mario and Princess Toadstool's tanker truck, Princess Toadstool, who was riding on the truck's top, threw a bag of Bob-ombs into Thunder Birdo's snout. Seemingly unaware of the Bob-ombs in her snout, Thunder Birdo tried shooting an egg at Princess Toadstool, only to blow up in the process, seemingly killing herself.