Cuckold Tears
The pre-cum which oozes from a cuckold husband's erect penis while watching his wife having sex with another man. This is a sign of his acceptance, approval (not that it is necessary), and overwhelming happiness seeing his wife fulfill her role of Hotwife.
As Monica was giving oral to her lover (i.e. Bull) she glanced back at her nude husband and noticing the pre-cum, cuckold tears, seeping from his erect penis