The US reality star vowed to fight the Page 3 model after she entered the contestants' shared bedroom after a shower and dropped her towel in front of Heidi's husband Spencer Pratt.
The blonde had already complained about Lacey showering naked in full view of the other housemates instead of wearing a bikini - calling her ''super inappropriate'' - and this time she threatened her with violence when she deliberately exposed herself.
Heidi said: ''Lacey's just got naked while we were in there. It gets me mad, that's for sure.
''I'm the new Paula [Hamilton]. I'll start swinging water bottles in a second. I'll fight her right now, she's got nothing on me.''
When Spencer finally calmed his wife down after former 'Heartbeat' actress Tricia Penrose joined their conversation, Heidi continued to moan: ''I don't wanna be around it, not around me and my husband.''
The 20-year-old model shocked viewers of the Channel 5 show earlier this week when she ran across the garden patio naked after apparently forgetting her towel.
However, it has been suggested Lacey was acting out a desperate attempt to save herself from tonight's eviction (16.01.13) after being put up for eviction alongside Heidi and Spencer, Rylan Clark and Claire Richards.
Commenting her actions in the Diary Room, jockey Frankie Dettori revealed: ''She's making an extra effort to sing and dance and stand out, when I don't think it's really her.''