You are handed a guitar and asked to play something....

hollywoodrox

Lil devil  by The Cult always sounds good  

It’s always tempting to go through various Riffs 
everything from Bon jovi ,RATT and leppard to cutting crew and nick kershaw and Duran .

acoustic  probably hotel California , take it easy ,tequila sunrise , dead flowers , every Rose has its thorn , wanted dead or alive ,freebird , some Bryan Adams , highway to hell, blaze of glory or anything I can recall at the time 

Woodenhead

Clean/acoustic Van Morrison's Moondance or something arpeggiated, RHCP's Snow - with lots of mistakes and, "wait I've got it now" thrown in.

OD/dist I fall into chugging the low E gallop style, The Trooper, Battery, etc.

Matt_McG

I used to have some Bach memorised, and a piece by Mertz. This: https://youtu.be/ksmgJlpm7ro
although not as well, of course. Worth listening  past the intro as the main melody is lovely.

These days, I’d have to just play something jazzy or gypsy-ish. But I don’t have anything that sounds good solo memorised. Which is a bit embarrassing.

Balrog68

Wish you were here, here comes the sun, Friday I'm In Love, love walked in, dead or alive... Various classical pieces or blag it with some randomly generated fingerpicked chord sequence... Usually the latter!

Phil_C

Electric - Sultans of Swing/Money for Nothing or anything Eric Clapton for the older ones. Or even Pink Floyd.

Even Johnny be Goode gets a good reaction

Acoustic, a lot of Queen, Oasis, Green Day, Ed Sheeran.

My musical interests know no bounds

Forgot to mention, sometimes rock licks just suffice.

DLM

DLM said:

Animal noises

Or this, net result is usually also "animal noises"...  

https://www.youtube.com/watch?v=F5QCs3PnQBc

soma1975 said:

On Electric:
Sometimes the Always on the Run riff. 

That's actually quite a solid shout, if we're gonna be serious here.

octatonic

Donna Lee head.

Philtre

Just don't hand a guitar to John Otway.

octatonic

Philtre said:

Just don't hand a guitar to John Otway.

What the fuck did I just watch?

Philtre

octatonic said:

What the fuck did I just watch?

The great John Otway. Try this classic:

Philtre

This is how John Otway would handle your guitar if you handed him one:

octatonic

Good grief.

PolarityMan

prob just random tool riffs

or maybe nothing else matters

prowla