To identify the phrase signifying "to procrastinate or delay something," an analysis of each option is necessary:
- Call it a day: This idiom signifies concluding work for the day or finishing an activity, unrelated to postponement.
- Put off: This phrasal verb denotes delaying or postponing an action, which is synonymous with procrastination.
- Break the ice: This expression refers to alleviating tension or facilitating comfort in a novel environment, not concerning delays.
- Blow off steam: This phrase means to discharge accumulated energy or emotions, particularly stress, and does not relate to delaying.
Consequently, the accurate selection is "Put off", as it precisely corresponds to the definition of "To procrastinate or delay something."