[MP2]

sizeof doesn't count as 'using it'. 'rand' is just storing a random value, and you're displaying that value. Change 'rand' at the end of format to RapesNames[rand]. You should really use STDnames or something though - they're STDs, not 'rapes'.

Also, the grammar/English in that formatted messages is bad, try this:

%s has been infected with %s by %s

or

%s has infected %s with %s (better imo)