Would this have anything to do with Lincoln's health problems in 1864 & 1865?
My guess -
That Abraham Lincoln enjoyed Chinese food and Mary Surratt made killer egg roles that John would deliver after adding poison he obtained from the pharmacy were David Herold worked.
Which reminds me of this song, that unknown to most historians,
when John's plan didn't succeed and according to a hidden message that was mysteriously uncovered in 1959 and turned into the lyrics for this hit song, Mary Surratt may have had a house guest (Confederate Spy) named Ivy Ladala (last line of the song) who would sneak around the White House at night trying to poison Lincoln or spread smallpox.