And the offer is! Buy any tickets for one show in the autumn season, and get tickets half price for a second show. Buy two shows and see a third for free! So I've just managed to get two pairs of tickets, all for £30. And for some rather good seats. Cheap theatre tickets galore!
It can be done in person or over the phone, or by pre-ordering online, but not with ordinary web sales. And it doesn't apply to previews. See here for the small print of the offer, or visit the Young Vic's What's On page for more about their season.
Happy 40th to the Young Vic!