Tullius asked me to find creative ways to disrupt the Stormcloaks. So as I left Solitude, I went by the Haafinger Stormcloak camp. I went in and stole everything not nailed down, and pickpocketed all of the weapons and armour off the soldiers. (Ok, so they'll get in some new weapons + armour; but Tullius only asked me to disrupt operations, not to destroy them entirely).

Other suggestions?

Walk up to Ulfric, thu'um him, and then run like hell out of Windhelm.

I'm not well familiar with the mechanics of this, but if possible, drop a legion cuirass. A guy picks it up and goes 'hey, can I have this?' Say 'sure, it's yours.' He puts it on. Now everyone in the camp is glaring at him

Reverse pickpocket full Legion/Imperial Armour and Weapon sets onto all of the soldiers.

The actual meaning of this dialog was lost due to 11/11/11. But in the current game, the closest you can get is sneaking into camps and taking all the food and supplies out of their barrels and laughing to yourself quietly.

I killed them with Drums....I had a good laugh at least. They were disrupted by the sound of a drum beating someone's head.

Humorous, but could potentially backfire, because this may help Stormcloaks act as saboteurs behind the lines.

Wabbajack them all into chickens! It may take a while and a few saves to turn them all into chickens, but it would be hilarious.

You cant do that remember the punishment for killing a chicken in Skyrim

He didn't say to kill the chickens. However if they joined in on a Stormcloak attack I would hope the NPC's would recognize that they are now the enemy.