The Last Supper was exactly that - a meal.
I think they were having the passover feast. When Jesus broke the bread and drank the wine he told them to do this in remembrance of me showing them that he was the sin offering. The new covenant. In my understanding he was saying no longer do this in remembrance of the old testament, but he was establishing the new testament.
Ezekiel 45:20-22
21In the first month, in the fourteenth day of the month, ye shall have the passover, a feast of seven days; unleavened bread shall be eaten.
22And upon that day shall the prince prepare for himself and for all the people of the land a bullock for a sin offering.
Matthew 26
17Now the first day of the feast of unleavened bread the disciples came to Jesus, saying unto him, Where wilt thou that we prepare for thee to eat the passover?
18And he said, Go into the city to such a man, and say unto him, The Master saith, My time is at hand; I will keep the passover at thy house with my disciples.
19And the disciples did as Jesus had appointed them; and they made ready the passover.
20Now when the even was come, he sat down with the twelve.
21And as they did eat, he said, Verily I say unto you, that one of you shall betray me.
22And they were exceeding sorrowful, and began every one of them to say unto him, Lord, is it I?
23And he answered and said, He that dippeth his hand with me in the dish, the same shall betray me.
24The Son of man goeth as it is written of him: but woe unto that man by whom the Son of man is betrayed! it had been good for that man if he had not been born.
25Then Judas, which betrayed him, answered and said, Master, is it I? He said unto him, Thou hast said.
26And as they were eating, Jesus took bread, and blessed it, and brake it, and gave it to the disciples, and said, Take, eat; this is my body.
27And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it;
28For this is my blood of the new testament, which is shed for many for the remission of sins.
Luke 22
19And he took bread, and gave thanks, and brake it, and gave unto them, saying, This is my body which is given for you:
this do in remembrance of me.
20Likewise also the cup after supper, saying, This cup is the new testament in my blood, which is shed for you.