There are 5 ways of how foreign words are adopted into Chinese. 

     1. Pure Phonetic 

Since some English sounds do not exist in Chinese, they are "transliterated" using the sounds that Chinese people consider closest to the original ones.  Thus, the "th" in marathon becomes "s", and as there is no "v" sound in Chinese either, "volt" turns into 伏特  fu2 te4. 

馬拉松  ma3 la1 song1 -- marathon 

雷達      lei2 da2 -- radar 

迪斯科  di2 si4 ke1 -- disco 

歇斯底裡  xie1 si1 di3 li3 -- hysteria 

巴黎 Pa1 li2                      Paris
紐約 Niu3 yue1                 New York

哥倫布 Ge1 lun2 bu4         Columbus
華盛頓 Hua2 sheng4 dun4     Washington

     2. Ideophonetic 

This one, although preserves as much as possible the original sounds, also tries to use the characters corresponding to the
meaning of the word. 

維他命  wei2 ta1 ming4 -- vitamin ("supports his life") 

潤絲      run2 si1 -- rinse ("moistens [your] hairr") 

香波      xiang1bo1 -- shampoo ("fragrant wave">)

引得      yin3 de2 -- index ("pull and get">)& 

     3. Phonetic + Semantic Classifier

Here, the phonetic equivalent for the foreign word is complemented by the Chinese word classifying the meaning of the whole
word. 

啤 pi2 (phonetic for "beer") 酒 jiu3 (Chinese word meaning "liquor") = beer 

卡 ka3 (phonetic for "card") 片 pian4 (Chinese word meaning "card") = card 

芭蕾 ba1 lei2 (phonetic for "ballet") 舞 wu3 (Chinese word meaning "dance") = ballet 

吉普 ji2 pu3 (phonetic for "jeep") 車 che1 (Chinese word for "car") = jeep 

乒乓 ping1 pang1 (phonetic for "pingpong") 球 qiu2 (Chinese word for "ballgame") = table tennis 

In some cases, in the course of time the Chinese semantic classifier becomes omitted: 

扑克 pu1 ke4 ("poker") is now used without 牌 pai2 ("playing cards") 

坦克 tan3 ke4 ("tank") -- without 車 che1 ("vehicle") 

白蘭地 bai2 lan2 di4 ("brandy") -- without 偽s jiu3 ("liquor") 

     4. Phonetic Rendering + Semantic Rendering

This one is not very common -- one part of the word follows the foreign word's prounciation, the other part conveys its meaning in Chinese.

冰 bing1 (meaning "ice") +  激淋 ji1 lin2 (phonetic for "cream") = icecream 

浪漫 lang4 man4 (phonetic for "romance") + 主義 zhu3 yi4 (meaning "-ism") == romanticism 

     5. Pure Semantic Translation

This is the most popular way of adopting foreign words into Chinese. 

飛 fei1 ("to fly") + 機 ji1 ("machine") = airplane 

受 shou1 ("receive") + 音 yin1 ("sound") + 幾 ji1 ("machine") = radio 

While many technical words and professional terms are normally translated using the 5th method (e.g., 電話 dian4 hua4 ("electric" + "talk" = telephone), the majority of commercial products, especially foreign food,  get their names phonetically preserving the original foreign "cool" flair for the sake of marketability. A good example is the obsolete usage of the not so savory 汗衫 han4 shan1 ("sweat" + "shirt" = T-shirt) by now almost totally replaced by the more hip T恤 T xu4 (phonetic for T-shirt).

漢堡包 han4 bao3 bao1 = hamburger 

色拉 se4 la1 = salad 

威士忌  wei1 shi4 ji4 = whiskey 

三明治 san1 ming2 zi4 = sandwich 

咖啡 ka1 fei1 = coffee