"Party Time" joke

"Are you coming to the office Christmas party tomorrow night?" the young man asked his colleague.
"Well" replied his friend "I'd like to but I'm afraid I've got to stay home. My pet will become very anxious if I stay out late."
"Pet?" replied the young man "I didn't know you'd got one. What is it?"
"A centipede."
"A centipede? That's unusual" But that's no problem. Why don't you bring him with you?"
The colleague agreed and the young man said he would collect him from his home.
On the following evening the young man knocked his colleagues door and found him pacing up and down the hallway in an impatient manner.
"Ready for the Christmas party?"
"No I'm not" he replied.
"What's the problem?"
"I've been dressed for absolutely ages and Percy's still not ready".
"Percy?"
"Yes, my centipede. For goodness sake Percy, hurry up. We'll be late for the party at this rate."
Percy did not respond.
After a few minutes the colleague called again, but this time he was extremely cross.
"We're fed up with waiting for you. If you don't come right away we're going without you."
"Oh shut up!" an extremely irritated centipede replied. "You know I always have trouble getting my boots on!"