S02E18: Cat Got Your Brain

Two evil bungling alien scientists transport Pidsley the cat and Shaun aboard their flying saucer. Unfortunately, a foolish error causes the aliens to swap the animals' brains around. Shaun and Pidsley are dumped back to Earth, not realizing they are in the wrong bodies - leading to much confusion around the farm before the aliens return to correct their mistake.At the end, everyone's brains were also swapped.