Hamsters are cute.
So that all goes without saying, and since those fuckers are so god damn cute, everyone needs an excuse to get one (especially a robo dwarf hamster); and this is my mine.
Unfortunately, I will never be PI, and that is a shame, because I have the best idea to get people to work on the weekends.
You go out and buy a cute, little, adorable hamster. And then you bring it to the lab. You show all your grads, undergrads and postdocs the hamster (which we will name Labby). You tell them about how the lab needs a mascot and Labby is going to be it. He will be just like a kindergarten class pet: he will serve the purpose of being cute, thereby putting everyone in a good mood, you will tell people that they can not yell or lose their tempers in front of Labby, or he will get upset, and if there is a gas leak from one of the cylinders, Labby ,with his fast respiration,will die first and give everyone that extra ten second head start.
And then you tell them that you hate hamsters. Especially Labby. This is important, you have to pretend that you have absolutely zero emotional attachment to Labby whatsoever. Shut up, this isn't the first time you have lied and you know it.
You casually leave hamster food and water in the lab, along with a note from the pet shop that explicitly says that hamsters must be fed each and every day.
Come back to lab on Monday. If Labby still lives, you have succeeded in getting your staff to work on the weekends. If Labby has died, then you are going to have a really interesting group meeting and this is that excuse you needed to do some firings. If Labby is missing, then you should double all your analyzed data versus the raw files, because some shit isn't right.