It's really not about the dom making you do it... It's really about whether you will accede to the request/demand.

And that depends a lot on how you rate the activity.

A Hard Limit (whether you realized it initially or never thought of it until it was mentioned) no, you shouldn't have to do it... but that also depends on your negotiated agreements. Some say a slave has no limits. (Not me, but some do.)

We have a limits and likes questionaire in one of the threads... and you might come across something that you've never done, never thought about, have no real interest in, but might answer "Only if my Dom really wanted it."

The line between these two is a fine one... and may even move. Do it once and it's a limit forever after... v. It's a limit... but gosh, my dom really really wants this of me (and you just love pleasing him/her more than you think you hate this....)

In my opinion, there is no advice that can be given about this that does not require you and your dom resolve this between yourselves.

We can't tell you yea or nay (unless it's patently illegal or life-threatening.) And even then... the most risky of acts can be mitigated with the proper precautions. (If someone asked me to jump from a plane or go base-jumping, it just wouldn't happen, yet people do it everyday.)