It might seem strange that one can make a list of his most favorite false friends. But what I am referring to are words (in English and German), which sound to similar to consider that in fact they mean something completely different.
I had to think about them while listening to the radio news yesterday. They reported about a press conference president Obama gave on August 5th, explaining his view on the recent nuclear agreement with Iran. This is what Barack Obama said:

…And by the way, nuclear material isn’t something you hide in the closet
The German reporter translated it as following:
…Übrigens kann man radioactives material nicht in der Klo-Schüssel verstecken
what would literally mean:
…And by the way, radioactive material isn’t something you hide in the lavatory

Even if we accept the sloppy confusion of “nuclear  material” with “radioactive material”, the difference between both perhaps not even Obama himself is aware off, the translation of closet (in american english a small room, usually for redressing and storing closes in) to the German equivalent of lavatory is really violating the meaning of the speech. Where as the lavatory is indeed a suitable room to hide a gun, or a lover , or dead corpse in, radioactive or nuclear material is better stored in the closet, since in this dry atmosphere one does not has to worry about corrosion of the uranium or plutonium.
The lavatory is unsuitable to store radioactive material also for another reason. In particular after one has taken a shower or a hot bath, and in cases of insufficient ventilation, the air in that room can quickly become over-saturated with humidity. And what happens than can be nicely seen in a cloud chamber in a radiation physics lab: Radiation produces beautiful, large tracks of foggy appearance. And this beautiful tinny clouds would immediately reveal the hidden stuff to an investigator. This would even be a cool idea for a Monthy Python sketch: The IAEA inspectors come to Ali Chameneis house to discuss which sites in Iran to visit. One of the inspectors asks politely if he might use the rest room, but Ali Chameneis wife is still occupying it, while taking a hot shower. After 10 minutes she returnes back, and – wrapped just in a stars-and-stripes towel – tells the foreign guest that he can enter now. As soon as the IAEA inspector enters the humidity saturated room and switches on the light, this is what he sees:

https://i0.wp.com/i.imgur.com/EFOdjXu.gif
Cloud chamber showing different tracks of radioactive decay products from air-borne Radon, cosmic and terrestrial radiation. The video is in real time, in a dark room with indirect illumination (from reddit.com)

But now back to the initial subject of False Friends (At least for now, I don’t want to refer to Ali Chamenei any more).  When native Germans learn English, there are more cases when (as in the case of closet and lavatory) one is prompted to use an easy-looking translation. And here comes the list of the most prominent ones:

ENGLISH WORD Assumed German Meaning (wrong) confused with the German word:
closet lavatory Klosett
eventually probably eventuell
sea lake See
probe sample Probe
handy Mobile Phone Handy
chef boss Chef
to realize s.th. to implement etw. realisieren
eagle hedgehog Igel
bald soon bald
public viewing open-air transmission Public Viewing
smoking tuxedo Smoking
money bag Wallet Brieftasche
gift poisson Gift
Indians native Americans Indianer
fabric factory Fabrik
hose pair of trousers Hose
chimney Fire Place Kamin
to rock s.o. to stone s.o. j.m. steinigen
sympathetic likeable sympathisch
to please s.o. to ask somebody a favor bitten

Just to avoid the accusation that I try to make fun on the expense of a single nation: I have to admit that some of the worst (and most resilient) False Friends I heard from non-German speakers. A colleague of mine from an Eastern-European country always says “a Probe”, if in fact he refers to “a Sample”. The reason is perhaps that both in German and in Slavic languages a sample is called “eine Probe”, whereas a probe should be precisely translated as “eine Sonde”.

Also native Indians (despite them growing up with a sort of English) are – in contrast to native Americans (see table above) – not free from using wrong words or phrases all over again. One PhD students in our institute, if he wants to ask a question, always starts the sentence with  “I have a doubt: …..” (Maybe in Hindi, the words “question” and “doubt” are not as different in their meaning as they are in English ?).  Another Indian PhD student girl finishes every sentence in her scientific presentations with the phrase “… or something like this”.  Thats sounds really, really weired in science.  Can you imagine that Albert Einstein talks about how “… with increasing velocity the mass of an object rises, with a factor of the inverse square root of (1-v2/c2), OR SOMETHING LIKE THIS.” ?