I found some definitions of "shell out" as follows:

 - To spend a certain amount of money (http://idioms.thefreedictionary.com/shell+out)

 - To pay for something, generally applies to paying large amounts of money (http://www.urbandictionary.com/define.php?term=shell%20out)

 - Having to pay an amount of money for something, especially if unexpected or having to pay more than one thinks is a fair price (http://www.urbandictionary.com/define.php?term=shell%20out)

 - (informal) Pay (a specified amount of money, especially one regarded as excessive)(http://www.oxforddictionaries.com/definition/english/shell)

Can I define _shell out_ as "to pay an excessive amount of money unwillingly or angrily"?