I came in the ice cream
That's gross. Why would you do that in the icecream?
I was bored and wanted to do something interesting
You may be bored, but this is not the way to remedy it. That is absolutely vile to put bodily fluids into food. You should be ashamed of yourself and I hope that ice cream was only for yourself and not others to suffer with.
It's not like anyone would know otherwise. Why does it matter?
If you seriously gave that to someone then that is absolutely disgusting. I can't even say anything other than you shouldn't do that. If the person found otu they would hate you and likely get physically ill from it.