I seldom see this mentioned and feel that it should be a general guideline/warning, that I have learned the hard way.
When drinking alcohol and bdo at the same time, the bdo will convert into ghb AFTER the alcohol is completely out of the system. This means that if you drink four beer the bdo will kick after about two hours (individual value). The real danger in this is when you re-dose the bdo because you don't feel it kicking - it will just float around in your system "waiting" for the alcohol to be metabolized and then convert into ghb all at the same time. This ISN'T the case with gbl and ghb, which will mix fine with alcohol. Please KEEP this in mind when mixing bdo and alcohol. Else you WILL overdose with what else seems like a normal dose+redose.