Did Jesus sin by "lusting" to eat the Last Supper?
In Luke 22:15 Jesus said, "I have eagerly desired to eat this Passover with you...." Few notice that the word "desire" here is the same word translated as "lust" in Matthew 5:28. Matthew 5:28 is the "go to" passage for those who teach that things such as sexually desiring another person or masturbation are always wrong. It says, "But I tell you that everyone who gazes at a woman to lust after her has committed adultery with her already in his heart." The word "lust" is also translated as "desire" in other places. It could be a good desire such as when it says, "Whoever aspires to be an overseer desires a good thing" (1 Timothy 3:1). Obviously Jesus, Our Perfect Savior, was not sinning by "desiring" to eat the last supper.
But can desire be wrong at times too? Mere desire or lust isn't wrong in itself. The object of your desire along with what you're planning in your heart or what your desire leads you to do is what can make it wrong. In Matthew 5:28, the issue is coveting to steal (sexually speaking) another man's woman (or wife) without his consent (the word "woman" can just as easily be translated as wife). This same word is also used in the LXX (Greek Old Testament) when referring to "thou shall not covet" (Exodus 20:17). In that Old Testament passage it lists things not to covet: "anything that belongs to your neighbor."
Obviously you can desire to have some of the things that your neighbor has. In today's culture you could desire to have your neighbors lawn mower, desire to borrow it, or desire to buy it or own one like it for yourself. The problem is if your desire would lead you to steal it from him (or even if in your heart you would steal such from him if you could).
Desire or lust in itself is not wrong. Even sexually desiring another person can be completely fine and be a natural desire that is God given. Masturbating or looking at porn or finding another to be sexually beautiful can be fine. Of course, there can be abuse of such things and they can be inappropriate, sinful and harmful at times depending on the circumstances. But overall, this subject has been misunderstood and caused unnecessary guilt and unhealthy suppression that has harmed people!
Instead of feeling guilty just for having sexual desire and masturbating etc., we should be open with the Lord and in good conscious seeking His wisdom about moderation with these things. They can be used as a release of sexual tension and actually help one's Christian life and be God given gifts to enjoy. Or they can be harmful for others when done in a certain way. If you want to learn more about the myth that masturbation is always wrong or other Christian myths about sex, check out the book "40 Christian Myths about Sex" by Alex Williamson. Few other books have the balls to speak as boldly and biblically on this touchy subject and it has helped many people.