CNX, DATA, XNN, OMG and WOLK incoming transactions on my ETH account

[FesselSpiel]

I have received all kinds of incoming transactions of all kinds of "strange" coins I have never heard of or never seen before.
Such as CNX, DATA, XNN, OMG and WOLK.

Can anyone explain this?

[S4quence]

That's is a rather new way to promote stuff: if you've participated in bounties, airdrops or giveaways you might have left your address somewhere, and they use it to send you promo tokens, you can use them to either get a bonus while buying an actual stuff or to exchange it to their real coin during limited-time offers.