New Job + Old Material= New Laughs
I think one of the main reasons I've moved around so much career-wise is that I constantly struggle with writing new comedic material.
During a very stressful conference call at work where one of the projects that can't fail is failing (and that I'm 100% responsible for) I uttered and very nonchalantly "It looks like I picked the wrong week to quit sniffing glue." I'd say in a room of 20, half got the semi-obscure reference and the other half just wrote me off forever professionally.
If you've never seen Airplane, I highly recommend it. It's given me so much material over the years that I feel guilty I don't send monthly royalty checks to the Zucker brothers. I can only say that line once so I make sure it's in a very stressful situation with lots of people who are scared stiff. Sometimes it loosens everyone up and sometimes it gets me written up (as happened at AT&T Wireless) where I was forced to take a drug test that some week (I passed). It's always been a winner though.
A few of my others are:
1) "Jesus, that's more than I make in a whole week" (uttered quietly but just loud enough for someone close to me can hear after hearing a shocking dollar amount for a hardware purchase- more effective if you have lower paid subordinates around you).
2) Can we meet on Wednesday instead? I have to meet with my parole officer instead. (said in a muted tone when a boss or superior is listening a little too closely to my cell phone conversation).
3) "I haven't felt that awful since we watched that John Holmes film" (Another slightly altered line from Airplane again and uttered after I've come back from a sick day and tired of people asking me how I felt. I've never seen a John Holmes film (no, I'm not linking- google yourself...) but it always gets me some very strange looks.
Often, it's not about the material but more about the delivery. The second someone thinks your trying to be funny, you're not. And never, ever, laugh, smile or make contact after jokes like these. 90% of the joke is making people think you're serious and really like that. Seriously though, I need to get some new material...