Javascript, 85
for(r=Math.random,s="",i=5;i--;)s+="bcdfghjklmnpqrstvwxz"[20*r()|0]+"aeiouy"[6*r()|0]
If run from the console, output is shown. Explicit display would add alert(s) at 8 chars, still shorter than the other JS solutions.
Thanks C5H8NNaO4 and Howard!
