Lindsay Lohan — Rehab Is Gonna Ruin My Birthday!!!!

Exclusive 0322-lindsay-lohan-rehab-birthday-tmzDon”t you just hate it when court-ordered rehab totally ruins your birthday plans Lindsay Lohan does … and is telling friends she”s super bummed she”ll be turning 27 while on lockdown.

There”s no getting around it … Lindsay has been ordered to check-in to a rehab facility for 90 days within the next month and half, so her July 2 birthday WILL fall in the treatment zone … and she”s pissed.

To be clear … not about the whole rehab thing … just about missing her birthday (seriously).

We”re told LiLo had big plans — which involved throwing a party in NYC — but now it”s all gone to the crapper after she copped a plea deal with prosecutors and took rehab over jail

In case you forgot, LiLo has already been to rehab five times since 2007 — including one stint during her 21st bday as well — but none have stuck. Sources close to LiLo tell us, they”re hoping this next trip will finally sober her up.

Again … still beats jail.