Is there a single-word replacement for the phrase "friendly verbal duel"?

For example, in the following sentence, can we replace the phrase "friendly verbal duel" with a single word ?

Phelps invited Ted Frederickson, associate professor of journalism, to a ______________ (friendly verbal duel) on the issue of "homosexuals and the military"

I am aware debate is a possible word, but are debates always on friendly terms ? The stress is therefore on the word "friendly" in my question.


When people spar[verb] (or have a spar[noun]) over some topic, they have a friendly argument.

Phelps invited Ted Frederickson, associate professor of journalism, to a spar on the issue of "homosexuals and the military".

Phelps invited Ted Frederickson, associate professor of journalism, to spar over the issue of "homosexuals and the military".

ODO:

spar
NOUN

1 A period or bout of sparring.

‘Remembering the spars she had had with the brothers, she smiled.’

VERB

[NO OBJECT]
1.1 Argue with someone without marked hostility:
‘mother and daughter spar regularly over drink, drugs, and career’


A word with this connotation is banter:

an exchange of light, playful, teasing remarks; good-natured raillery. - dictionary.com


noun: repartee

conversation or speech characterized by quick, witty comments or replies.

synonyms:

banter, badinage, bantering, raillery, witticism(s), ripostes, sallies, quips, joking, jesting; formal persiflage

"an evening of wit and repartee"

-- Google


A bit esoteric, yet apt, is the word dialectic, which Aristotle referred to as the counterpart to rhetoric.

A dialectic is an informed discussion on any given topic which involves, among other things, verbal sparring; defining of key terms and appropriate qualifications for those terms; arriving at either a breakthrough or an impasse.

Persuasion is certainly on the fringes of a dialectic, but the guiding purpose of a true dialectic is to arrive at what might be called a transcendent view which incorporates the insights of all the participants, yet allows for modifications and refinements of, and amendments to, its tentative conclusions.


I'd probably use palaver. My assumption is that the meeting is for the benefit of Phelps, to help him frame the issues in the way they are likely to be framed by the media and the public, so as to come off a bit better in future, more public, discussions. The word has several shades of meaning, definition one is

1a : a long parley usually between persons of different cultures or levels of sophistication
1b : conference, discussion

And there is this historical note on the etymology -

During the 18th century, Portuguese and English sailors often met during trading trips along the West African coast. This contact prompted the English to borrow the Portuguese palavra, which usually means "speech" or "word" but was used by Portuguese traders with the specific meaning "discussions with natives." The Portuguese word traces back to the Late Latin parabola, a noun meaning "speech" or "parable," which in turn comes from the Greek parabolē, meaning "juxtaposition" or "comparison."

"Palaver." Merriam-Webster.com. Merriam-Webster, n.d. Web. 3 Jan. 2017.

I like this word specifically because the LGBT issue in the military has long been framed as a battle over "military culture" in the US.
https://www.cmrlink.org/content/military-culture-and-diversity
http://www.militarytimes.com/story/military/2015/06/18/glaad-military-roundtable-culture-change-gay-bisexual-transgender-lgbt-lesbian-homosexual-troops/28919291/