Nothing that would hurt it, just some behavioral experiment.
206311
The one thing a spider is afriad of is attack form overhead (primarily wasps looking to lay eggs) You could see if your spider is more of less likely to treact to different colours/shapes suspended overhead.  Or even how it would react to a mirror.
627891
AFAIK it doesn't hurt anyone, so no big deal here.
473498
might not if it was self induced
242063
IF YOU LEARN FROM IT,IT WONT BE A MISTAKE.
245206
U could try emotional freedom technique.
297008
Do the experiment.  You might learn something.
321438
I don't see anything wrong with it as long as its not taken as a gesture for something else just a little peck is fine
410672
There is know nice way.\nNo matter what someone will be hurt.
191185
it doesn't have all the side effects of other things...\nlook @ this...
345940
If it makes you feel uncomfortable, then don't do it.\n\nThat said, if the person you are jumping on has experience in doing demonstrations like this, and has said it's okay, then you don't need to worry about hurting him.  It's a pretty standard trick.
151836
not a thing. let them work it out or else something bad might happen and you could end up responsible for it
52649
A simple no would be okay
124358
I would say no.  ;-)  You're talking about nervous fidgeting, right?  I'm not sure why anyone would think that's dangerous.
202923
That's a perfectly reasonable experiment.  It addresses issues of solubility and phase equilibria.  As long as the project is done in a logical manner (i.e. following the scientific method), it should be a good project.
411423
THERES NOTHING WRONG WITH IT
7770
Most definately. Probabaly the most easy way to prove this is to read on animal behavior in the subject of embarassment or anxiousness. Have you ever seen a cat that has tried to jump on top of something and they goof up? Some might lick their paw in a moment of trying to recover grace or run away out of embarassment. I think these reactions are key indicators of animal self-awareness.
224735
yes, it may be harmful