I have been told this joke and I can figure out why it's funny, help! 'A man goes into a bakers and says can I have a large loaf please, the baker says brown bread or white and the man says it doesn't matter I've left my bike outside?

Whoever told you this joke is an idiot and understands it. You can't figure it out cause it doesn't make sense.. I'm an idiot and I don't get this but literally, It makes no sense -_- 

From re-reading the idiotic thing It's either 

• the man wanted a loaf of bread that was big enough to carry it on the bike but he couldn't bring the bike in or
•  just the person who told you it made a mistake while telling it... If not then whoever told you this sucks at joke telling...