Below is a macro that pastes unformatted text.
Code:
Sub PasteUnformatted()
'
' PasteUnformatted Macro
'
'
Selection.PasteAndFormat (wdFormatPlainText)
End Sub
Installing Macros
You can attach a keyboard shortcut to this and a QAT button easily.
Modifying the QAT and Ribbon in Microsoft Word