Anyone know why cellphones are called 大哥大 in Taiwan?
According to one of the rumors, the first cellphone was used and introduced by Sammo Hung, which is the elder kung-fu brother of Jackie Chan. Since at that time Hong Kong entertainment was fairly respected in nearly the whole East and Southeast Asia, most people showed their respect to call Jackie Chan as 大哥 and his elder kung-fu brother Sammo Hung as 大哥大. 

Then, clearly the cellphone being used by 大哥大 is 大哥大電話. However, after a while, most people simplified the usage and just used 大哥大 only.