Oral sex
From Tardis Wiki, the free Doctor Who reference
Tyler Steele once performed oral sex for money while homeless. (AUDIO: Hostile Environment)
Elton Pope was said to have a "bit of a love life" with the partially restored paving stone incarnation of Ursula, implying repeated acts of unreciprocated oral sex. (TV: Love & Monsters)
The doctor did not consider it as good as anal sex. (PROSE: Rose)