Concerning drinking cum from a condom found on the ground, it was a fantasy we had with an ex-girlfriend. The idea was we should be hidden in a small dark street, watching a couple fucking. The man should use a condom, in which he should came. After they fucked they should leaved, throwing the condom on the ground. Then my girlfriend should pick it and drink the cum...
Another one in the same style was we found the condom and she drank it, imagining it was used just a few minutes before.
We never realized any fantasies with cum of other men because of the risks of STDs.