I grow old … I grow old …
I shall wear the bottoms of my trousers rolled.
Rolling up your trousers is cool now!
At the time, however, it was the hallmark of a dweeby old man whom nobody would ever find attractive, powerful, or sexy ever again. He sees his life ahead of him ending with the kind of pathetic solitude and indecision expressed in the next two lines: questions like whether he should change the part in his hair will be the biggest decisions he’ll have to make now that he’s chickened out on trying to get with a real live woman.
To help improve the meaning of these lyrics, visit "The Love Song Of J. Alfred Prufrock" by T.S. Eliot and leave a comment on the lyrics box