ob

obvious

Example:

It's ob why they did it. They wanted the money.

odd-bod

strange person

Example:

I don't like Steve - he's a real odd-bod.

off one's trolley

stupid, eccentric

Example:

You're off your trolley. That's the craziest idea I ever heard.

off-the-shelf

available easily, standard

Example:

No problem, it's an off-the-shelf part. Got one right here!

old hand (at something)

to have a lot of experience with something

Example:

Franco's an old hand at web design. He's done it for 10 years.