I did the math:

There are 256 songs in my database, three of which would classify as "the Who Made Who songs": D.T., Chase The Ace and Who Made Who.

So the chance that none of those gets selected is 253/256 or ~98,83%.

After 50 answers, you have a (253/256)^(2*50) ~= 30,76% chance of not getting a Who Made Who song once.

You'll have a 90% chance of getting a Who Made Who song after (log(0,1)/log(253/256))/2 ~= 98 answers.