Giant Syringes

I was browsing AliExpress as one does, and got recommended a giant 500ml syringe. As is expected, the picture is manipulated to make it look bigger than it is. But it got me wondering, could I use a large plastic syringe in some sort of fluids predicament. Now I should address, these aren't medical sort of syringes, more so the type for gently watering your plants, on a more excessive scale. 

The largest I could find was a 1500ml, with most being at most 550ml. 

Here's the 1500ml, and it has some smaller sizes. 

https://s.click.aliexpress.com/e/_DCUBU7j

My main thought on how it might be used is some sort of standing predicament, where if you wanted to give your legs a rest, you would have to sit on the syringe and push it down into your ass, and pushing its contents inside. Now I don't think I found anything big enough for that, but I was wondering what sort of ideas you might have for these almost novelty sized syringes

Seems easy enough, but could be difficult to do.
Something like mounting a dildo on a toilet seat and tieing yourself so that you can only stand with your knees bent halfway up.
You can’t stand because you’re tied to the seat. You can’t sit eather, or the contents will shoot into your rear.

So, how can this be done, that’s the tricky part. I tried this a few times without bondage and got nowhere.

The only thing I can think of is to somehow insert a dildo that is hollow for a syringe could fit into. But then again, it would have to be tied to you to keep it from slipping out.

Another way would be to get one of those doughnut cushions, fill it with water and connect it to rectal cathedral. The catheter stays in place while the cushion stays on the seat.
Sit on the seat squishes the cushion and the water shoots inside you.

That’s how I would do it.

At some rate it just becomes an enema bag that you can squeeze for pressure, though the big limitation is that your range of motion in bondage is less than that of the syringe plunger.

The first use I can think of is if you bolt it down a bit and screw a plate into the top of the handle you could drop weights onto the plunger for it to dispense liquid. You could then just figure out what method you want to drop the plate. One idea is to tie yourself sitting down and have the plate directly below your feet, if you put your feet down it triggers the plunger. Mind you that has relatively little force. Another is to have your arms held above your head with them being tied to the plunger with the output end facing down, if you put your hands down, boom, water in ass. Or have it under your heels when in a tip toe position, let your heel down and water goes in butt.

You could consider using the setup in reverse too, have the plunger be upside down to generate suction, for example it could be attached to the end of a penis expander thing and punish by pulling harder and harder.

If you are a Rube Goldberg fan you could have it go both ways, which is particularly interesting if you want to force nasty drink situation. Connect the end of the syringe to a T-joint with a one way in side and one way out with the syringe in the middle. The biggest challenge is to create a situation where pumping action occurs, an idea off the top of my head is for the plunger to be connected to a belt at the hip with a spring on the plunger, then have the belt wearer be tied to an uncomfortable chair that forces you to get off which pulls on the belt and pulls liquid, when you inevitably sit down the spring pulls the plunger back down and the liquid takes the only viable path out to wherever you want. In theory you could have it set up so you drink a large amount of water to start, have another decent quantity in the input tank to start and have the output be connected to a straw which goes to the mouth, creating a closed loop.

That’s a good idea.
Eather way, you’re correct. It’s pretty much an enema bag you sit on.

Almost any other way would just as complex as what you just described.