Because he lost her number, Ted spends every Halloween for the next several years at the same rooftop party, wearing the same "Hanging Chad" costume, hoping she will show up again.
She wrote her phone number on a Kit Kat bar wrapper , which Lily accidentally gave away to a trick-or-treater later that night. [S1E6] Slutty Pumpkin
In the How I Met Your Mother episode , "long paper" likely refers to the Tootsie Roll Because he lost her number, Ted spends every