(Steel drums) Thank you for calling Carnival Cruise Lines. There has never been a better time for a luxurious vacation to beautiful Haiti. Discounted travel executions are now available. Pay no attention to the truth less rumors of unrest, there has never been a better time for a luxurious vacation in beautiful Haiti… 
Used ONLY for prank calls from kids!!!
The 3rd time they call I say “911, what’s your emergency”, it works because they think I forwarded the call.
Unclviny
I use this in the evening when I answer the phone and get that pause just before the telemarketer comes on…
Delivered in my best NCO voice…
“Bravo Battery 5th Battalion, 28th Feild Artillery, Sgt. Jimson speaking how may I help you sir or mam.”
Not very original I know, but exceptionally effective. (I’m sure someone will point out it’s likely not entirely legal impersonating a military base and all. But if anyone is supid enough to confuse my split level home in Ohio with Ft. Sill OK that’s their problem.)
Back in college, a friend’s answering machine message was:
“This is the (college town) Strategic Air Command Nuclear Missle Storage Facility. Please leave your name, number, and desired target location. We will return your call shortly after the missiles have launched. Have a nice day. BEEEEEP.”
It was funny the first time or two, then it was simply long.
At about the same time I was using the schtick SnoopyFan posted.
When you answer the phone hold a large cup up to your mouth to get an echo effect: “Welcome to Mc Donald’s, may I take your order.”
(Change out fast food restaurants and greetings as necessary)
End conversation by asking the caller to pull forward to the window.
This is only funny if both parties have seen Fight Club.
You: “Maintenance 1888.”
Them: “Uh…”.
You: “It’s under control, sir.”
Them: “What?”
You: “Don’t worry about us, sir. We’re solid.”
I had a roommate in college who loved this sort of stuff. One of his favorites was, “Student Affairs: want one?”.
Others: “Bob’s cookie jar - what crumb do you want?”, and “County Morgue: you stab 'em, we slab 'em”.