They're always switching their tails!
Because its head is on one side and its tail is on the other.
Re-tail.
Hay Fever!
Because he's a horse racist.
Two. One to find the switch...the other to hit it.
She switches from Ragu to Prego.
Two. One to identify that the lightbulb has indeed burned out, and one to call the maintenence man to change the lightbulb.
Listen closely.