Draw from implied imagery using words that may seem unusual in the situation.
Generally, good writers advise to avoid adverbs. Use a word that speaks for itself, bringing your meaning from its situation.
Consider...
"slopping" (oneself with a towel)
Slopping myself with the towel, I gazed out the window at the commotion below.
Since "sloppy" is the description you are going for, simply use "slop" as your verb.
"flopping" (the towel)
I stepped out of the shower, grabbed the towel without looking, then started flopping it around my body.
The advantage of "flopping" is its phonetic similarity to "sloppy", the idea you are going for.
"dabbing" (oneself)
I dabbed at my soaking wet body while glued to the TV.
"Dabbing" is not in itself a "sloppy" work, but as a means of drying oneself with a towel—that would likely describe an effort that is sloppy by implication.
"throwing on (the towel) like a cape"
Exiting the water and throwing on his towel like a cape, he darted inland.
This is a little farther from your idea, but it still works and is a usable example of what you can do.
Likewise, consider others: slapping, smacking, mopping, brushing, flapping, rolling, et cetera.