Don't worry about the spelling. Just drink the beer. All beer is $2 today at Bacchus.
The difference is simply in what gender the word is referring. When referring to a woman with yellow hair, you should use the feminine spelling “blonde”. When referring to a male with yellow hair, you should use the spelling “blond”.
This then is one of the few cases of an adjective in English that uses distinct masculine and feminine forms. Another is fiancé (male) and fiancée (female).
Bikini Blonde from Maui Brewing company isn't really what the sailors come to Bacchus for… but it's worth a sampling and for $2, it's a great bargain. One reviewer is quoted in saying the beer,