"Is your refiger running?"
"Is your refrigerator running? You better go catch it!"
Hey, genius! The joke is that "refiger" sounds like "refrigerator." Then, the setup asks if your refrigerator is running (like, functioning). But the punchline plays on the literal meaning of "running" as in escaping or moving quickly. So, you better go catch it because refrigerators don't have legs, dingus! Also, you should consider investing your time in something other than posting lame jokes like this one.