For the first time I encountered "tät" when it appeared in this subtitle to a TV episode:

> 
> Ich **tät** ihr ein paar Schlaftabletten geben.
> 
> 
> 

So I searched DWDS and found [many other examples](https://www.dwds.de/r/?q=%40t%C3%A4t&corpus=zeit&date-start=1946&date-end=2018&format=full&sort=date_desc&limit=50).

Duden says that tun can be used "used to describe the subjunctive". But the subjunctive is "täte", not "tät", again according to Duden. So what is "tät"?