"Shovelling coal into the server..."
"My other load screen is much faster. You should try that one instead"
"The version I have of this in testing has much funnier load screens"
"Loading a virus, please relax while your life's work is being deleted..."
"HELP!, I'm being held hostage, and forced to write the stupid lines!" gamdaaaaa
"Want to see a funny loading message? Take a look
here"
"Why so serious?"
"Ouch! Careful where you point that thing!"
"Press Alt+F4 for a quick IQ test" "Adjusting data for your IQ..."
"Improving your reading skills..."
"Waiting for approval from Bill Gates..."
"Warming up Large Hadron Collider...""Searching for Answer to Life, the Universe, and Everything"
"Please don't move..."
"Please count to 10..."
'Please wait and and dream of faster computers'
"Counting backwards from infinity""Who is General Failure and why is he reading my hard disk?"
"Program loaded. Please enter the square root of 598309209839 to continue.""Press any key to continue" User presses a key. "NO! Not that key!"
and this will be epic :

collected them from
SO, check for more