Credit: Marc Broussely/Redferns

They tried to make her go to rehab and she said yes, yes, yes.

"Rehab" singer Amy Winehouse, 27, checked into The Priory rehab clinic on Wednesday -- but not before stopping at at Meadway Food and Wine in Southgate, North London to buy a miniature bottle of Smirnoff.

"She seemed out of it," an onlooker tells The Sun. "She was stumbling about, slurring her words. I was shocked to see her buy vodka so early in the day, and even more shocked to see her knock it straight back."

The singer's rep tells Us Weekly that Winehouse checked into the facility because "she wants to be ready for performances in Europe this summer and decided to seek an assessment. She will remain at The Priory on doctors' advice."

This isn't Winehouse's first stint in rehab: the "Back to Black" singer sought treatment in January 2008 to treat her addiction to drugs and alcohol.