The general story of why we can't in general is because there's no surprise, there's no mock aggression, and also there may be a general deadening of self-stimulation.

为什么大部分人不能胳肢自己,是因为它在我们意料之内，没有打闹的侵略性，通常这种引自己笑的念头都会嘎然而止。

耶鲁公开课 - 心理学导论课程节选

There's no aggression or bad feelings towards the British at all.

BBC: British entrepreneurs invest in Bulgaria

There's no aggression, no hurt, no harm.

NPR: Iran, Britain at Impasse over Captives

There is no aggression in the gesture.

BBC: Honduras's child killings