butt (up) against (someone or something)
1. To be positioned physically next to someone or something. The table is just a little too long—it butts up against the wall over here. Our neighbor's new addition butts against our bushes, unfortunately.
2. To crash into someone or something. My daughter got hurt when another girl on the soccer field butted against her. My car is in the shop because I butted up against a barricade on the highway.
butt (up) against someone or something
to press against someone or something firmly. This board is supposed to butt up against the one over there. The goat butted against Fred, but didn't hurt him.