Дикарь normally means something like 'savage' or 'caveman' (an uncultured person), but can be used colloquially to refer to a person who undertakes a поездка дикарем (without advanced booking--think of a 'backpacking Europe' type vacation). In Soviet culture vacations, unless you just wanted to stay around home, were either of a 'отдых' (rest) nature where they'd spend time at a spa/camp/sanatorium type environment or of a 'туризм' (tourist) nature, involving travel, usually along a predefined route with scheduled activities. Usually to take one of these vacations you would need to acquire a 'путевка' (voucher), either by purchasing it or perhaps receiving it as a reward at work or from an acquaintance if you were well-connected. It was sometimes fairly difficult to get a путевка, especially to one of the higher end spa resort type places, and even more so for an entire family at once. A person could also go somewhere as a дикарь, without a путевка, although doing so could be problematic when it came to finding good lodging/food.