Tankero is a common Finnish term for Finns who speak English with a really bad accent, or worse yet, write English using Finnish grammar. This pseudo-English is consequently also known as "tankero-English". (In case you've never heard a really bad Finnish accent, recall your favorite Hollywood movie featuring sadistic Nazis saying things like "Ve haff veys to make you talk", and make the accent ten times worse.) The word comes from the following story:
Foreign minister Ahti Karjalainen was visiting a small African country, and naturally his hosts took him on a safari. They drove for miles on a rattling jeep, and finally encountered an elephant. Ahti pointed at it with his finger, and remarked: 'Tankero!' His main host, the local foreign minister, smiled heartily, and nodded in agreement not to offend his guest.

They kept on going, and crossed a small river. There were some hippos bathing in the water, and our honored foreign minister pointed at them saying again: 'Tankero!'. The local host laughed a bit, and agreed: 'Yes, yes', but was getting seemingly confused at the same time.

The sun was getting close to the horizon, and pretty soon they had to get going back to town. While they were returning on their tracks, they suddenly noticed a lion laying down in the high grass. 'Tankero!' was Mr Karjalainen's remark again. Now the African minister, puzzled, turned to the Finnish minister's aide, and asked: 'What is he trying to say?' 'You'll see soon' was the humble reply, and while they were crossing back through the park's entrance gate they noticed a big sign with a warning: 'All animals are dangerous.'

Based on a translation by Markku Verkkoniemi

It's worth noting that Karjalainen is the Dan Quayle of Finnish politics and there are plethora of similar jokes about him. This one does, however, seem to be fairly well substantiated -- although in some variants the setting is the London Zoo instead.

The reason Finland has so many tankeros is that Finnish does not have any voiced ("soft") consonants like b, d or g. While these letters are (these days) often found in loanwords, they are usually hardened when pronounced, the end result being that Finns eat pananas, go to MkTonalts, and play kolf. Finnish also has a very phonetic writing system, which makes grappling with English spelling a very tankeros exercise indeed.

Put no vörries: Finnish youf are kettink petter änd petter ät Enklish, so fese tays most no lonker sound like Nazi konsentration kämp kuards and tankeros häve pecome an entankeret spesies.