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2.
A Scots word meaning a penis, usually large and floppy, often used as an insult
I have a huge walloper

I don't like him, he's a walloper
by big hairy walloper August 03, 2006
 
1.
person as useless as a floppy dick
you're burning my dinner ya fuckin' walloper
by alistair January 12, 2004
 
3.
Derived from the word wallop, which is onomatopoeia (a sound word) for an impact of some sort, it is a Scottish slang term for a penis, usually a large penis.

It is also used to refer to unpleasant people, much like dick, cock, prick and knob would be used in conversation.
"Jesus Christ, did ye see the size of that walloper he had on him?"

or

"He's a bleedin' walloper, and that's all there is to it!'
by Kraigy January 17, 2007
 
4.
Sydney Australia slang for a police officer. Based upon the belief that police are inherently violent, and therefore if they speak to you then you are likely to be walloped (beaten, assaulted).
I saw the wallopers patrolling past my house but they didn't stop, so someone else must be in line for a beating tonight.
by House Martin February 18, 2013
 
5.
A cock (see Alastair). Usually big
Alastair has a wee nob, I have a walloper!
by Jimbo February 23, 2004