The example sentence 'die Tante zum Kaffeetrinken überfallen' is translated as 'to spring the aunt on a cup of coffee'. This is incorrect, it should be 'to spring a cup of coffee on the aunt' (or better: one's aunt). The example given is implying that a cup of coffee is being surprised by the aunt. Not only does it sound very unnatural as a native speaker, but you can even see in the entry that the correct structure is 'spring [sth] on [sb]', whereas the example sentence uses 'spring [sb] on [sth]' (incorrect). Hope this helps!