An Assassin can skip Decepti0n's initation hand animation by ADS. Is there a way for a Mechromancer to skip her similar Deathtrap summoning animation?
The only way that I've found to skip the animation is to go into a menu. So inventory, Badass Rank menu, Mission Logs and so on.
I have not tested this in multiplayer, so it might not work there. Should it work in multiplayer you usually can enter and exit it quickly enough so that it shouldn't put you at too much risk of dying.