Terrible, as there is nothing, in the least bit, oxymoronic about it.
If you think there is - you don't know what 'socialism' means, or maybe you don't know what 'democratic' means -but either way, if you think these two things are contradictory that's your ignorance, not my mistake.
It may shock you to learn that even Karl Marx was an avowed democrat - more than a few of his contemporaries favored communist revolutions yet none happened during his lifetime - because he personally intervened and kept stopping them. He sincerely believed that if socialism was not achieved via democratic means, that it would degenerate into a dictatorship with all the horrible consequences those always have.
I would argue that the fate of the USSR and related revolution-created communist countries proved him right.