On: Regex Golf

[shdon]

Excluding doubled consonants that have the same vowel on both sides of the pair:

  ^((?!([aeiou])([^aeiou])\3\2).)*$

The following also works for the testcases and is shorter:

  ^((?!(.)(.)\3\2).)*$

[surreal → shdon]

Can get 2 more points with:

  ef|^((?!(.)\2).)*$

But I reckon yours wins for having a pair of breasts in the middle