You might want to be careful about pasting anything remotely sensitive into the URL bar as most browser automatically send your query to the search engine for auto-complete functionality.
I never changed my habits from Windows; I use the Run box, or type leafpad / mousepad. It's interesting that we've independently invented the same technique.
- If the text to sanitize is a single line: Win+R, paste, select all, cut, Esc (to close "Run" window)
- If it's multiple lines: Win+R, notepad, Enter, paste, select all, cut, Alt+F4 (to close notepad)
On Linux, I usually switch to Emacs, switch to a scratch buffer, then do the paste-and-cut-again dance in it.