give sth up as a bad job

give sth/sb up as a bad job (to stop doing something because you do not feel it is worth continuing) — ≈махнуть рукой на что-л. (отказаться от дальнейших попыток); считать безнадёжным; махнуть рукой на кого-л. / что-л.); ≈ поставить крест на ком-л. (или чём-л.); ≈ плюнуть

Example 1: After three attempts to explain the joke I gave it up as a bad job. (CIDI)

Example 2: I started a crossword puzzle last night, but it was too difficult for me, so I soon gave it up as a bad job.

Example 3: When he failed his exam the second time, he gave it up as a bad job.

see also
[опускать руки ]
[give up the ship]