When Snape heard the thrumming noise coming from Dumbledore's office, he had taken that as a signal Dumbledore was being attacked. Shouting out the password to the gargoyle, he charged up the stairs, wand at the ready. He flung open the door. And froze.

Dumbledore had his back turned to from him and was listening to Shakira's 'hips don't lie'. But nothing disgusted Snape more then seeing Dumbledore had wrapped his long, silvery beard around his waist, using it as a sort of waistband so it swished to and fro when he shook his bony ass.
As Dumbledore swayed around on the spot, Snape saw he had a goofy smile on his face and his glasses were pushed up onto his rather balding head.
Snape, his mouth askew, could not figure out what to say.
Dumbledore's sixth sense kicked in, however. He looked up to see Snape, with a mixture of bewilderment and mortification on his face. He gasped.

Untying his beard, he held it against his body as a person would hold a blanket against their nakedness.
Pulling his wand out of one of the pockets of his robes, he pointed it at the rather worn out stereo sitting on a small table at the corner of his office. It immediately silenced.

"Bloody hell, Dumbledore, what are you playing at?" asked Snape when he had finally found his voice.
"I don't understand what you are talking about, Severus," replied Dumbledore, taking a seat in his armchair by the desk and looking innocently up at Sbape as if nothing had happened.
"The dark lord is out there protesting war against us and all you can do is...is...bellydance"
Dumbledore looked down. Snaoe's fury heightened when he realised Dumbledore was not feeling guilty.
"Get a grip!" roared Snape angrily.
Dumbledore did get a grip. But in the wrong place.
Pulling it out of his robes, he waved it at Snape threateningly.
"Get out of my office, Severus," he said quietly. "Before I rape you"
"W-w-what?!" asked Snape, aghast.
Dumbledore looked serious. "Now, Severus," he said, his voice dangerously low.
When Snape still didn't move, he got up.
"Crap!!" screamed Snape, lunging for the door." At the same time, he screamed at Dumbledore 'Get away from me'
Finally seizing the doorknob, he rushed out of the office. He had better warn Flitwick. That's if he wasn't already a victim to this...