To close one's eyes; to close one's eyes tightly.
Why are your eyes closed? (This has the idea that maybe there is s.t. wrong with the eyes.)
Why are you closing your eyes?
The reason I'm closing my eyes tightly is because I have s.t. in them.
To wink at s.o. (as an indication that you are just kidding s.o.)
I winked at him so he would know that what I said was just to kid his wife.