The guys in his squad were sick of him.  He was an ass and a douchebag. He was continually talking down to them and was a bully, picking on any guy smaller than him.  Most everyone feared him, since he would beat men who crossed him. During their last leave he even slept with several of the guys girlfriends.  It was time to take him down a peg, but no one was willing to stand up to him, fearing the retribution.  

During their next leave, a group of the guys decided to get tattoos to permanently commemorate their friendship and time in the service together. Even though they did not like him or invite him, he came along with them, wanting a tattoo himself. The guys all got small matching tats on their biceps, but being the ass that he was he wanted a big tat on his back.

Something military to reinforce his masculinity. Joking with the other guys that they were not men enough to get a real tat. The guys suddenly saw their chance, and pooled their money to pay the tattoo artist to modify the design.

Back in the barracks, he pulled of the protective wrap the artist had put on to prevent infection and proudly showed the squad, not knowing about the modification.  There was a collective gasp from the soldiers, as they saw his new ink. The men realized that this gave them permission to get even with his bullying ways, and gang bang his muscular ass. Bending him over, the first of his squadmates rammed his dry cock into his ass. The taking of his cherry was incredibly painful, and the guys loved it.  For the next eight hours he was raped hard and cruelly by the men he served with. A series of grudge fucks, made his ass open up and get filled, to overflowing, with grunt spunk.

For the rest of his military career he was used, as his tattoo suggested, as a cum dump for infantry men.