Do you know that I tell people I got a speeding ticket if I'm running late to something? I actually haven't gotten a ticket in 4 years now.
I hope you are just joking because why would you pretend to be late to something?
I don't want to get yelled at.
It's great that you are able to save face like that, but you are just making excuses for your irresponsible behavior. You need to come clean and stop lying, because someone will finally catch up and wonder what you were really doing before being late.
You are right, I should tell the truth but my co-workers don't deserve to know
That's cool that you agree, and I think it's only going to help you by being honest. As for your co-workers, you have the right to not let them know, so just ignore them. Since they are not your boss, you actually don't need to justify anything to them.