TRAFFIC is overused.
Some of the ones I recall
These are all actual excuses personally told to me.
I was in jail.
My helper was in jail
I had to bail out my helper
My van got repossessed.
There's a boot on one of the wheels of my van (parked in someone else's driveway)
I forgot where I parked my van last night.
Someone broke into my van last night and stole my steering wheel. I had to steer with a pair of vise grips.
And my all time favorite:
Carpet installer explaining why he was five hours late in picking up the goods.
Someone snuck into my bedroom last night and took the batteries out of my alarm clock.