The same is relevant for "Birdie" and "British", whilst "British" in certain UK accents is pronounced something like "Birtish" ... that makes these two callsigns sound a lot alike !
But how about waypoints - in Norway, on the stretch between Oslo and the South West coast there are some waypoints within a confined area, that can sound the same. Apart from Sola (Stavanger), there are a great number of points starting with SO, strangely enough they are all on the FIR boundary dividing ENSV and ENOS - named from the south:
SONAV-SOSOL-SOTIR-SOGLO-SOPAS-SOPAR-SOGRA-SOPEN-SOMAG-SOBOD-SOMES and then there are the NDB's near Oslo named SOKNA SOLBERG.
They are all different all right, but the kind of controller likely to put the pressure on the first syllable will let SOPAR and SOPAS sound alike, when they omit the trailing 'ssss' of SOPAS. These two points are less than 30 miles apart - and it doesn't help either, that Norwegians have a special 'twist' of wowes (sp?) where "a" becomes "arg" or "r", "o" becomes "oo" or "u", and "u" becomes "yh" (!) - this makes "SOPAR" sound like "SUPAR", and "SOGLO" sound like "ZUGLU" ... If you know this, or can guess where they want you, it is no problem, but to newcomers, you would often need a few "say agains" ...
Aren't these points made up in ICAO, Eurocontrol or somewhere central ? Wonder why these points had to be so similar sounding.