The reading for this one is all kun'yomi vocab reading, but you should know these by now. 着 uses the reading you learned with 着る, but this word employs that pesky rendaku, so remember that き becomes ぎ here.
Koichi is wearing special boxers today.
We must ship all of the underwear orders on time.
Which underwear do you want? The plant or animal patterned ones? Pick whichever one you like.