First off, may I congragulate you on making such a big suggestion topic.
Now, Here are some of my ideas...
• When going into the casino it is possible for a moment when looking to the right or left to see a group of men robbing it. With the name Oceans on their shirts.
• When in the poster area there is a chance all the posters will be slightly modfied and they will watch you. Buying a poster duing this time (30 Sec) will get you the poster.
• When you go into water there is a chance it will turn yellow for a small bit.
• When you go into water there is a chance it will turn brownish for a small bit.
• There is a chance that when on the beach seagull's may swirl around you and try to decapitate your head. A small cubit bonus would be rewarded for surviving. (or just the inconvinience)
• There is a chance when entering gamerooms that unused boxes will have a ally cat in the corner of them. Duing this time there is no invisible wall stopping you from getting in. If you have a fish from fishing and lure the cat in (like minecraft (I guess, sigh....)) you gain Ally Cat as a pet. There could be different color variations of the cat.
• When on the ferris wheel there is a chance that when on the top of it when looking at the ocean, you may see an elusive rob jumping in and out of the ocean with graceful dolfin movements.
• If weather is implemented when raining there is a chance you will slip or trip.
• Whenever you log on you may get the message. I feel lucky today or I feel uneasy today. These effect condo specific easter eggs. (Also, if you feel uneasy, you will trip when running in the lobby. Your jetpack will sputter out too.)
• When looking around with a metal detector you can find a aged metal. If you get all the pieces they make a statue. (this is less of a random event I guess but it would be cool)
• On TVs that arent being used, a cryptogram may play. Using blurred speech among other things. Decoding this would unlock a secret. Or item.
• When crouching and walking it is possible to suddenly become flat like a pancake during this time you can buy the pancake modifier.
• When swimming, subtle music can be heard in the background. Similar to the jaws music...
• Adding on to the one I just said when you hear this music a shark may come to eat you. If you or any other player gets eaten, the water turns a shade of red for a bit.
• At night when driving a boat, it is possible to see a haunted boat. If you bump into it, it will dissapear and you will get a ghost ship pet.
• At sunset when driving a boat it is possible to encounter a typhoon that will send you and your boat crashing on shore. (this makes it a double random event)
• If eating is implemented and donuts are added there is a chance to "Choke" on the donut hole.
• In the movie theater there is a chance that when unused various news reports may play. Explaining story wise. How the zombies came to be, what Tower Unite is, and various things like that.
• In the movie theater there is a chance that when unused a news report may play about zombies from another far away island swimming across the ocean to Tower Unite.
• When sprinting for a long time you may have stars start to go across your screen and someone saying "Activate the Hyperdrive!". You are then wisked off to just floating in space. Until something happens to make you go back to TU... You will then get a small amount of Units for the inconvienince.
• There is a chance at night, all the NPC's for about 1 minute will have a fnaf4 style to them. Not scary because its overdone but still messed up, freaky.
• When chatting there is a chance text will occasionally come out rainbow.
Then two seconds later it will go back to normal (so you can actually read it)
• In the condo when you join you may see someone with a mask on and holding a bag jump out of your window very quickly.
• This person will occasionally be seen in the lobby after this. If you can catch him everyone on in the lobby gets some loot and the person who captured him will get a fair bit of Units.
I'm not done yet but I have to do some stuff. I guess I will post more later.