BAJ

Brunei is going through the BA? series for vehicle registrations, and it is interesting to note which combinations are skipped.

BAD was omitted, so we went straight from BAC to BAE.

And we have recently found that BAI is also omitted, so we went from BAH to BAJ.

The reason for this is presumably because bai means 'pig' in Brunei Malay, and nobody would buy a car with its registration number reading 'pig'.

One can try and speculate which further sequences will be skipped ― but I can't think of any likely candidates at present.