Going to prison (bit naughty)

My wife was allowed to visit me one last time before I started my prison sentence.
"I've baked you a cake," she said, "And I've hidden something inside it that might help you in there."
"What is it ?" I asked nervously, "A tiny rock hammer ?"
"No silly, a tub of Vaseline!"
"I've baked you a cake," she said, "And I've hidden something inside it that might help you in there."
"What is it ?" I asked nervously, "A tiny rock hammer ?"
"No silly, a tub of Vaseline!"