1. 2. Sex.
Katie Wales speaks about the eroticism which appears in Ulysses through sound-play, and she quotes the following fragment:
"Tipping her tepping her tapping her topping her. Tup. Pores to dilate dilating. Tup. The joy the feel the warm the. Tup..."
Here, as Wales explains, the words with a "t" and a "p" give sexual innuendo to the phrase as they are phonically similar to the word "tup" which has sexual connotations.
(Section 4 in "Joyce's Use of Imagery in Different Topics")