The best excuses I've heard are in the Mighty Boosh book:
I was doing an etching of Alan Sugar talking to a whirlpool.
Monty Don asked me to glue sim cards to his karate belt.
Brigitte Bardot put me in a time capsule with a picture of an orange cat holding a rifle.
I drank over a 1000 Yakults last night and when I woke up, I was made of solid light.
I was having a penalty shoot out with a ghost of a flea.
I was auditioning for the part of "ham face silver lips" the mosquito version of Tron. (They said I was too camp)
I was killing owls with Diego maradonnas frozen shin pad.
I met a human rocking chair called Captain Suck Force.
I spent 3 hours climbing on top of the worlds biggest nurofen.
A Japanese man with a frozen face blocked my wind pipe with tin foil and Buckaroo instructions.
(visual one) Come in riding a giant notepad, muttering, "space sauce" over and over, then fight an invisible doctor.
A number 7 threatened me with a tennis ball.
I was with nanny bar code.
