A rapid, steep rise (e.g., in prices, popularity); skyrocketing.
最近、家賃がうなぎ登りで生活が苦しくなった。
Recently rents have been skyrocketing and life has become harder.
彼女の人気はうなぎのぼりで、テレビの出演が次々と決まった。
Her popularity has been rising rapidly, and TV appearances were booked one after another.
株価が鰻登りに上がり、投資家の注目を集めた。
Stock prices shot up and attracted investors' attention.