This is what I say...
"It's real but got it cheap because it's stolen."
"Is that your real hair?"
"On the record? It's a fake. Off the record? It's real. "
"It's not necessarily not unlike the real thing." (By the time they figure that out, you're gone.)
"Of course it's real, you can touch it"
"It's a hallucination."
"The watch is real, I'm a fake."
"It's a trick watch."
"It's as real as me sleeping with your wife!"
"It's real but I replaced the band, case, and movement."
"I don't know if it's real. It came with my artificial arm."