to fester, to be a pain in the neck
[verb]
[et-te-ren, et-ter-de, ge-ët-terd] 
The verb ‘etteren’ has two main usages: in the medical sense it is the festering of a wound, but in daily life it is most likely showing annoying and pestering behaviour. Based on the latter translation a number of terms of abuse are in popular use: ‘etter’ (or ‘ettertje’), ‘etterbak’ and ‘etterbuil’, whereas the last one is the only one referring to the medical meaning (with ‘buil’ being a lump or swelling).
Examples:
– “Jongens, nu ophouden met etteren daar achterin of we gaan helemaal niet meer naar Disneyland!”
(“Guys, I want you to stop being a pain in the *** back there or we won’t be going to Disneyland at all!”)
– “Het kind van de buren zit al de hele dag enorm te etteren, als dit zo doorgaat doe ik hem nog eens wat aan!” – “Ja, het is inderdaad een etterbakje, maar misschien moeten we het met de ouders bespreken…”
(“The kid next door has been an enormous pest all day long now, if he continues like this I’m going to hurt him at one point in time!” – “Yes, I agree that he is a pain in the neck, but perhaps we should discuss it with the parents…” Note the use of ‘iemand iets aan doen’: to do something to somebody / to hurt somebody.)
– “En nu allemaal luisteren! We gaan zo het museum binnen, en ik wil geen geëtter, iedereen gedraagt zich netjes, is dat begrepen?!”
(“Everybody listen up! We are about to enter the museum, and I do not want any nuisance, everybody is going to behave properly, is that understood?!”)
– “Waarom willen ze niet meewerken dan?” – “Ach weet ik veel, ze lopen expres te etteren. Het zijn allemaal etters daar!”
(“So why are they not cooperating?” – “Oh I don’t know! They are deliberately being a pain in the neck. They are all a bunch of bastards!”)
Related words:
– Etter(tje): pain in the neck [noun] [de (het) etter(tje), de etter(s/tjes)].
– Etter: pus [noun] [de etter, <no plural>].
– Etterbak(je): synonym for ‘etter(tje)’ [noun] [de (het) bak(je), de bak(ken/jes)].
– Etterbuil: synonym for ‘etter(tje)’ (somewhat less friendly though), or: abscess (medical) [noun] [de (het) buil(tje), de buil(en/tjes)].
– Irritant: irritating, annoying [adjective].
– Vervelend: annoying [adjective].
– Recalcitrant: recalcitrant [adjective].
– Balorig: contrary, recalcitrant (mainly of children) [adjective].
– Pesten: to pester/badger/plague [verb] [pestte, gepest].
The alphabetical overview tells me that we have not covered many words starting with ‘J’. So, to improve the situation, today’s word is ‘jennen’. The verb ‘jennen’ in general is less serious than ‘pesten’ which can take the meaning of ‘to bully’. Also, ‘jennen’ is used when you are teasing somebody with the objective to annoy, as opposed to ‘pesten’ which you can also use to tease somebody about say a physical characteristic. A synonym of ‘jennen’ is ‘plagen’ however I have the feeling that the ‘annoyance factor’ is bigger for ‘jennen’.