You can not drop anything unless your make a specific action to do so wich includes pressing "yes" to an "are you sure" prompt AND yuou must be still alive to do so.
Sould you do the specific action tro drop somehting anyone who sees it can hen grab it unless you do so in an estate you own.
In the case of an estate you own you will not get the "are you sure" prompt.
Someone Elses estate is the only place in EU where you can not drop anything.
PVP. In 99% of the pvp zones in EU the only thing you can loose is hitpoints and only temporarily at that.
In 1% of the pvp zones specifically PVP3 wich is located south of Camp Echidna, northeast of Chimera Canyon and northwest of Fort Pandora.
In That pvp zone you have the possability of loosing any strackable items you posses on your avatar except loose peds and and ammunition (and i think mind essence).
That means in that zone and that zone only you would lose any dung, sweat, enmatters and minerals, animal parts (including hides and reseduses)
and the new stackable robot parts and only if another player kills you while there.
It is impossable to go into PVP3 by "accident" unless you had previously bought an anti-toxic shot applied it and forgot about it.
To enter that zone sufficently enough to be looted by another player you must first go to the TT buy an anti toxic shot, then, equip it and use it.
In addition to that you will also get a couple of warnings that you are entering the lootable zone. Including a warning in the little message box that is used for "hints" and to let you know if someone outbid you on auction as well as where you find out if someone just sent you a PM.
If you encounter a pvp zone that is not limiteds to amethera, one of the 3 major pvp zones on eudoria or the octagon rings and anywhere you can go within 30 seconds of leaving such a pvp zone.
If you are killed by someone in anyplace other than the above mentioned places (like around PA) you have encountered a bug and should submit a support case explainign the location (press P while in game to get the location) circumstance and as much other info you can to MA.
The person who killed you in such place also risks sanctions by mindark for bug exploitation.