When two people are talking a lot and flirting and maybe getting intimate however are not officiallygoing out so they are just on tings with each other
'What's going on with u and Jade'
'Ah nothing offivial we just on tings you know'
Also known in the txt world as ODT. On Dis Ting can refer to someone who is committed to an act where others would have deviated or fell short due to laziness, cowardice or lack of self confidence.