To do something or attempt to do something like a lord. A lord can be regarded as a wealthy, well to do layabout who eats and drinks excessively. The term like or as a lord tagged onto the end of a sentence would imply that you did something to excess, further in excess for example, of something you did like a gentleman. If you drank like a lord, you would have drank a tremendous amount invariably leaving you drunk as a lord.
I drank plenty last night. I drank so much I was drunk as a lord.
I had a huge meal last night, I was stuffed after it. I ate like a lord.