Trying to stand on top of a huge monster?

[Skuli]

Ok, so, here's the setup - my DM just throwed me in the middle between two half-tyrannosaurus/half-dragons and ended game for today. I'm pretty much in a dark place. BUT my character is pretty much optimized for the job, just they need to not hit me :D
But a theoretical question - let's assume I can teleport on top of one of the monster back. So... now what? I assume that the tyrannosaurus dragonus won't be too much pleased about my idea and will try to knock me of his back, especially I'll try to smack him in his neck. Are there rules in place to deal with that sort of situation? It's not grapple, well, I can try and hold myself to his neck or wings, but well, it's not grapple. Besides, I don't suppose I would stand a chance. So... any ideas as how to aproach this kind of "bull riding"?

[Nifft]

1 - Ride checks.

2 - Balance checks.

3 - This-is-awesome-I-don't-need-no-steenkin' checks.

[Skuli]

Yeah, that's my first though, well, with balance thing mostly. But don't have a clue as to oposed to what/how difficult the check would be ^^ Need to prepare myself for whatever DM may don't know, and, think about if I shouldn't just... "run, Forest, run!"

[flappeercraft]

I would make it a strength check by the tyrannosaurus +4 per size category larger than you, opposed by your balance check.

[Remuko]

Also it would be easier to just call them Half Dragon T-Rex's or T-Rex Half Dragon's based on your description. Its a lot less of a mouthful than how you keep describing them.