I splattered one of our worship leaders full on in the face with a custard pie while she was being prayed for and slain in a big outpouring of the Holy Spirit! It was kind of an accident. It was at a youth service where she'd custard-pied me in a quiz in front of a load of teenagers, so I decided to exact my revenge at the end of the meeting. I saw her laughing and I thought "now's my chance" so I got her and then realized by the shocked look on the faces of people around her how inappropriate the timing was. Apparently she'd just been telling those who'd been praying for her how peaceful she felt with the Holy Spirit, when suddenly - splat! It happened years ago, but we still laugh about it now. It was hilarious!
Oh, I've just thought of another one. It was my friend's wedding and I was playing guitar in the worship band. The signing of the register seemed to go on for ages so we were asked to blag another performance song. So our worship leader innocently (non of us thought about this) started playing "All the Way" by Delirious. We then realized that everyone was cracking up laughing their heads off because the words of the chorus are "Today, today, we're going all the way!" Oops!