The other day, in conversation I said jokingly:
Oh, ma guardati! Devi aver fatto un viaggio lunghissimo... I tuoi vestiti sono sporchissimi! Quasi quasi ti faccio spogliare e te li lavo!
Here I wanted to express the idea of "I’ve a good mind / half a mind to make you strip off and ...". In English, this expression is used in a rather disapproving, threatening tone, even if half-jokingly, when you are faced with something unpleasant. It also implies that you are not likely to follow through with the threat you've made or whatever action you just said you were going to do, after all.
"Quasi quasi" at least conveys the idea that the threat may or may not materialise – that’s a given. But I'm not sure if it can carry a disapproving, threatening tone perceived in the English expression – all the more so since I use "quasi quasi" in a positive context as well:
Quasi quasi vorrei restare sempre bambino!
This sentence (due to its positive tone) cannot back-translate as "I’ve a good mind / half a mind to do X".