Time Complexity Puns

Perfect 10, but purely imaginary.

This was one of her favorite jokes she loved to tell: One day, a man was walking home after a long day at work. As he waited for a crosswalk signal, he glanced back and noticed a coffin standing down the block. "Odd," he thought, but he ignored it and continued home. He turned the corner and managed to catch a glimpse of the coffin again. This time is was closer to him... like it was following him. He picked up his pace and ran into his apartment complex. The coffin was right behind him. In a fright, he dashed up the stairs to his place, locked the door and barricaded himself in the bathroom. Thud, thud, thud! The coffin was banging on the bathroom door. The man frantically looked for something to defend himself. Just as the coffin busted through the door, the man grabbed some cough syrup from the medicine cabinet, threw it at the coffin ... and the coffin stopped.