This is a true story: my friend's voicemail says, "Hi, you've reached Dave, I'm screening your call." My friend is a recent college graduate, currently searching for a job. While your best friends might think it's funny, anyone else will see a message like this for what it is: unnecessarily rude.
Using your cell phone to record a voicemail message isn't always easy. Between remembering what to say and getting the right timing, it's tricky. But your phone does have a playback option, and it's easy to listen to and review your message. For some people, though, cutting off the end of a message is a funny way to trick people and catch them off guard. In most situations, callers won't know it's intentional and will think you're far less than tech savvy. Definitely not an impression I'd want to make.

(make a little noise in the background). Hi, you’ve reached your friend’s house. He/she isn’t home right now and I took the opportunity to rob it. I was about to steal the machine as well and you called. After the beep, leave your name and number. I will write it on a post-it and leave it on the refrigerator for him/her to see. Oh and one more thing; where did you say you lived?
Another way to make up funny voicemail messages is to act like a device has come alive. For instance, you could say,"Hello, I'm Bob's hair dryer, and I've taken over because I'm way more interesting. If you'd like to leave a message for him and have your hair dried at the same time, just hold up the phone." Answering like an answering machine, a microwave, or refrigerator and using the functions of that device in the answer are easy ways to create a fun voicemail.