Interesting and unusual things to do for a fiver or less this week.
Monday 23 September
PRIVATE EYE: The satirical magazine's Ian Hislop and Nick Newman are at the National Theatre discussing the funniest and most influential of Private Eye's cartoons from its 50 year history. £4 / £3, prebook, 5.45pm
SHORTS: Watch new short films and animations with Bar Shorts at The Book Club in Shoreditch, plus DJ Kung-FU plays between screenings. Free, just turn up, 7pm
COFFEE: MR PORTER are giving away free coffee at various Taylor Street Barista shops each morning this week. Today it's Canary Wharf. Free, just turn up, 8am-10am
Tuesday 24 September
QUIZ: The You're Going to Need a Bigger Boat Film Quiz is upstairs at The Ritzy in Brixton. £4, first come first served, 7.30pm
CRICKLEWOOD GREATS: Discover film and TV programmes connected to Brent at Wembley Library. Free, just turn up, 6pm
MERMAIDS: Discover mermaids through history, from London coffee shops to the Wellcome Collection, with a talk at the Hunterian Museum. £4, prebook, 1pm
Wednesday 25 September
MARS: Professor Carolin Crawford talks about the robots exploring Mars, and what they've found, at Gresham College. Free, just turn up, 1pm
PODCAST: Geekatorium presents Richard Sandling, Paul Gannon and Eli Silverman recording podcast The Uncliquables at the Camden Head. £3, just turn up, 7.30pm.
SCIENCE LATES: The Science Museum opens until 10pm with events covering game theory, maths and the Underground, 1860s photography and a silent disco. Free, just turn up, from 6.45pm
Thursday 26 September
ROBOTS: Artist Alex Kiessling is creating a new piece – in Vienna. But a robot in Trafalgar Square will mirror his movements and make its own work. Free, just turn up, 10am-5pm
FORTEAN LONDON: Four speakers talk about labyrinths, magic, marshes and the curse on Eddie and the Hot Rods for the London Fortean Society at The Bell pub on Middlesex Street. £3 / £2, just turn up, 8pm
Friday 27 September
JULIEN TEMPLE: The Portobello Pop-up Cinema finishes Julien Temple/Fest with a screening of London, The Modern Babylon with guests Will Self and Temple himself. £5, just turn up, 7.30pm
OPEN DOORS: Go behind the scenes at some of London's current construction sites and talk to the people making it all happen. Also on Saturday. Free, prebook, 9am-4pm
ART: Over 50 new artworks will be projected around Dalston's Gillett Square (indoors and outdoors) for Night Contact multimedia and photography festival. Free, just turn up, dusk-midnight
TEA: Learn about the Japanese tea ceremony over a demonstration at the British Museum. Free, just turn up, 2pm-3pm and 3pm-4pm
Saturday 28 September
WALKS: Go for long rambles all over the capital with Walk London. Free, just turn up, various start times.
HARVEST FESTIVAL: There's food glorious food at Abbey Gardens in West Ham; competitions, cupcake decorating, a quiz and music, plus tea and cake to buy. Free, just turn up, 1pm-4pm
BOYS AND GIRLS: Gender and identity is under discussion at the Bishopsgate Institute, and how they're expressed in our lives. Free, just turn up, 2.30pm
SOUL: Dance to soul records in the Betsey Trotwood's basement for a similarly basement entry price. 99p, just turn up, 8pm-1am
Sunday 29 September
FILM: Catch a screening of Wes Anderson's Moonrise Kingdom, starring Bill Murray, Edward Norton and Frances McDormand, at the Southbank Centre. Free, just turn up, 8pm
LATIN AMERICA: Rich Mix hosts two talks as part of the Latin American theatre festival CASA 2013, a photographic survey of Britain's Latin American community over the last 30 years and on theatre of exile. Both are followed by performances from Instrucciones para Abrazar el Aire. Free, just turn up, 5.30pm / 6.15pm
CHILLI: Celebrate the chilli pepper at Spitalfields City Farm with the Festival of Heat. There'll be a bar, live music, and more chilli than you can shake a chilli at. Free, just turn up, 12pm-6pm
Check out our map of free things to do in London for more frugal fun.
Photo by Savage Pink from the Londonist Flickr pool