A filthy-minded Bronx school custodian was arrested for asking two teenage girls if he could watch them make out, police sources said Tuesday.

Pastor Heras was collared Monday just before midnight for allegedly asking the two Walton High School students — 15 and 17 — if he they would kiss in front of him, sources said.

The 54-year-old janitor then offered to take the girls on Dec. 3 to a secluded area in the school where they could fool around — as long as he could watch, according to sources.

The girls reported the incident to the school, which then notified the police.