My brother and I (both straight) get crazy one night.
My brother is two years younger than me. We both masturbated and knew that about each other but we had never done anything together. One day I created a game called Animal Interactions. One of us would roll a dice and would pretend to be an animal based on the number they rolled and would be known as the mounting animal. The second of us to roll would do the same but would be known as the mounted animal for the round. Then the mounting animal would hump the mounted animal like the animal they rolled. The animals were something like this.
1: Cow. 2: Horse. 3: Elephant. 4: Dragon. 5: Dog. 6: Pig.
I also thought up some special actions we would have to do if we got a certain combination of animals.
Cow-on-Cow: Each cow must milk the other one's udder (at least 5 tugs on the penis).
Pig-on-Pig: Both of us had to bump our butts together at least 10 times.
Dog-on-Dog: The dog being mounted had to shake their butt in the air before being humped.
Elephant-on-Elephant: The elephant doing the mounting had to reach in-between the mounted elephant's legs and jerk his penis.
Horse-on-Horse: The horse being mounted had to fart or make a farting sound at least once while being mounted.
Dog-on-Dragon: The dragon stood over the dog on all fours while the dog played with the dragon's penis and balls.
Cow-on-Pig: The Cow had to stand over the pig on all fours while the pig suckled the cow's udder (penis).
Even though we were (and still are) straight, we both had a lot of fun. Maybe you can try it with your loved ones...