It rarely happens, all you have to do is find a safe spot with a bunch of other players from your team and attack the people that are spawn trapping. DUH.
For instance is someone is spawn trapping you from team 2 on the roofs and you are in the team 1 base go really near the buildings and want until they come near to the edge of the roof to kill you and you are already with a sniper ready to kill them. DUH.
But I mean REAL spawntrapping. Where they are already standing at your spawn in several corners, and when you shoot at one of them you will get shot in the back. How will you deal with that situation? DUH?
Try to throw a bomb at where you die if they are double teaming you, and if one is close and the other one is far away to keep distance the bomb will kill the close one and you will respawn and if you have the skill snipe the other one and you can take the height advantage if you are good at sniping or be a sneaky cat and kill them from the behind. DUH.