This depends on the context.
To diddle someone means to rip them off, scam them.
However if it is used like 'that test was a diddle!' it means that something was easy.
"Diddle" can have different meanings depending on the context. It can be a slang term for cheating or swindling someone, or it can refer to moving quickly and lightly. It is also a term for playing a simple tune on a musical instrument.
It is British slang for female genitalia.
It's British slang for an umbrella.
its a slang term for hello
Codswallop is British slang for excuses or lies. For example: 'Your dog ate your homework? What a load of codswallop!'
British Army slang from way back referring to women's breasts.
Bee's knees is British slang for 'fabulous!'. For example: 'Cor ol'chap, that meal was the bee's knees!'
A "fag" is British slang for a cigarette.
moving along smoothly
garage off
In British slang, the word "aggie" means agitating. It is directed at a person. For example "For crying out loud he is so aggie!"
In British slang, this means to fart. For example: 'Patrick please don't blow off in the car again'.