2
general::
Phrase(s): ride up (on someone)
1. Lit. [for someone on a horse] to approach someone, riding. • I rode up on him and frightened him. • I guess I was in the house when you rode up. 2. Fig. [for clothing, especially underpants] to keep moving higher on one’s body. • I don’t like it when my pants ride up on me. • I hate it when my underpants ride up.
McGrawhill's American Idioms And Phrasal Verbs