Istappar - 'icicles' are common these days. Is is 'ice' and tapp is same as 'tap' in English: tappen i tunnan is 'the tap in the barrel' or other elongated things such as pegs or tenons. En hötapp is 'a wisp of hay'.
The verb tappa means 'lose' or 'drop' but another meaning is related to tapp: 'to draw' for example wine into bottles or 'let run' water into a bath.
In western Sweden tapp can mean 'petrol station' but the most common word for that is mack.