A Texas couple turned a designer Manhattan condo into a virtual flophouse by renting their apartment to transient, hard-partying guests, a lawsuit alleges.

Robert and Marilyn Blodgett, of Houston, have allegedly used apartment 3K “as a vacation rental property,” drawing a “revolving door of complete strangers,” despite repeated cease-and-desist demands from the condo board of 340 E. 23rd St., the Manhattan Supreme Court suit states.

At least 27 tourists have bedded down in the condo unit since August 2011, but it was recent guest Malcolm Kee who sent residents into a tizzy, according to court documents.

Kee, in his mid-20s, checked in Jan. 14 and allegedly threw three raging parties, invited friends who threatened and cursed out building staff, and still hasn’t checked out, the lawsuit claims.

The Gramercy Condominium board wants to shut down the illegal hotel.

The Blodgetts did not return phone and e-mail messages seeking comment.