This weekend, Torontonians have a chance to be secret agents, improv actors and participate in yet another massive urban "scene" hosted byImprov Everywhere.

Mp3 Experiment Torontowill take place this Sunday at Riverdale Park at exactly 2:00. Participants are asked to wear a Red, Blue, Yellow, or Green t-shirt and bring an umbrella, an uninflated balloon and an mp3 player. Most importantly though, everyone must download the same mp3 and sync their watches so everyone can start listening at the same time. If you plan to attend, be sure to read thedetailed instructionsbefore you do.

If you somehow haven't heard of Improv Everywhere, it's kinda likeNewmindspace, but undercover. You can spend hours on their site going through the 70 missions involving thousands of undercover agents. Some of the highlights areFrozen Grand Central, where two hundred people simultaneously froze in Grand Central Station for five minutes,Human Mirrorwhere a subway car was filled with identical twins sitting on opposite sides of the car in mirror image, orFood Court Musicalwhen a dozen people suddenly broke into a musical in the food court of a mall, all unbeknownst to the hundreds of people who just happened to be there at the right time.

You might rememberTorontohad a taste of Improv Everywhere in January of this year when it was one of 10 cities around the world participating inNo Pants 2k8when over 2000 people went trouser-less on subway rides to work. This weekend though, Improv Everywhere will be having it's first Toronto only mission and everyone is invited to join.

Check out videos of previous Mp3 experiments below.

Two videos from thefourth Mp3 Experiment, where 826 people downloaded the same mp3, congregated on Lower Manhattan's beautiful waterfront and pressed play at the same time.

Mp3 Experiment Four: Part OnefromImprovEverywhereonVimeo

Mp3 Experiment Four: Part TwofromImprovEverywhereonVimeo.