-So my question is, is it possible to just mash them like with grapes and let it do it's thing?
-Do i have to wash it first?
-wouldn't the skin give off any foul taste to the final product?
Mash and let ferment - yes.
Wash - no, unless some kind of pesticide or herbicide was sprayed on it recently, then rinse with water.
Skins - not a problem.
However the resulting wine may be a bit tart and/or low alcohol. That's why most recipes suggest adding water and sugar.
It should do something, it might make wine, it might make vinegar, or is could just make a foul juice. that is the fun of wild yeast, you might get a fantastic wine or you might get nothing.
A failure is almost always the result of a poor process.
@bracconiere is right about vinegar; it's easy to avoid.
If I didn't have access to basic winemaking supplies, I would mash the fruit (freeze and thaw first if possible), add an equal amount of sugar water (about 13-18% sugar), cover with a towel to keep out insects, stir daily, transfer (siphon) to another container after about 5 days of active bubbling, cover that, trying to keep it air-tight (airlock if you can get one, otherwise plastic wrap and a rubber band might work), let that finish over a few weeks, taste it, if it's good siphon the liquid into another container and put that into the refrigerator.
Cheers