Fairy Tail Episode 299:

Death Guy: It's torture to have a naked woman in front of me!!

Mavis: I found a way to defeat Zeref!!

Later...

Natsu (posing naked): Nii-san... please... no more... it hurts....

Mavis (also posing naked and showing herself to Zeref): Zeref... you would really use me for such evil purposes rather than use for me for more... sensual acts...?

Zeref: (dies of anime nosebleed)

Oh, btw, this isn't what happens (or at least, I assume it's not, lol)