Wait for It
How I Met Your Mother Season 3 Episode 1 (09/24/07)
When Robin shows up with a new boyfriend, Gael (guest star Enrique Iglesias), Ted decides he's ready to move on and hit the town with Barney. While out he meets Amy (guest star Mandy Moore), a tattooed party girl that he spends the night with. Ted wakes up with a butterfly tattoo on his lower back (tramp stamp). Marshall informs Barney that he has 55 days until his next slap and shows him a countdown.