Saints Row 2 is a free-roam gang based shooting game. As is the situation with these types of games ANYTHING is possible so yea, maybe you will experience people nakedly car surfing while doing a handstand in online co-op.
Starting where the original Saints Row left off, your character wakes up in prison after having survived an explosion where you get the chance to customize your player before they "take the bandages off". An unknown prisoner gets shanked on purpose in a prison fight (can't make this stuff up) so he can help you escape the jail and whole story kicks of from there. The clothing company from the first game Ultor is now the embodiment of the seal killing, people hating corporation doing genetic experiments and killing "undesirables". They introduce the company early on and how it has ruined Saints Row and has to be stopped. But no. You don't spend the game taking down Ultor. You instead get dragged off to some side plot killing off three other gangs in a series of fun but tedious Missions and Strongholds. Once you kill off all three leaders you spend three measly missions killing the Ultor board of directors and kicking the CEO Dane Vogel very predictably out of his 100 story plate glass window. It is a known fact that even Stevie Wonder saw it coming since the first mission.
The three classics make an appearance here, single player, co-op and competitive multi-player. Single player mission playing is tedious at the best of times and the competitive multi-player plays like E.T. if E.T. had confusing and ridiculously complicated missions and tasks. It pretty much turns into everyone running around like a bunch of epileptic stoners, not knowing what is going on or what they are doing, just shooting because they have guns in their hands. Co-op is the one glimmer in the shit-pile of fucked controls and stupid missions that is the core of this game. As soon as another person is there its like the graphics arn't quite so shitty, missions not quite so tedious, mind much more disturbed. The things people will do to attract attention and go for shock value is probably illegal in most places (apparently not Stillwater, it's really hard to get police without directly shooting a cruiser) as when anything is possible, people are destined too be animals. If you've never seen a fat Chinese ginger stick a satchel charge to an oxygen mask wearing senior and proceed to both detonate and satchel charge and graphically tea bag the burned corpse for minutes on end you havn't experienced Saints Row 2.