• darn!, shoot! (mild oath expressing irritation, annoyance, etc.); hell, why not
• some people use the heck after words such as `how', `why', or `what', to emphasize a question.
• people use a heck of to emphasize how big something is or how much of it there is.
heck of a
• hell of a, remarkable, special, extraordinary (slang)
what the heck
• what the hell!, what is going on! (expression of surprise or anger)