I got caught out many years ago when learning to fly on a C150 with flap switch (not gated) and 40 degrees available. Solo student at the time in the circuit. Climbing out from a touch & go and I retracted the flaps on the runway......but must have knocked the switch back down again when moving hand from there back to the throttle......the climb out became very interesting in both pitch and airspeed until I noticed the ever increasing flap angle! Luckily I was solo and light on fuel so got away with a prompt re-retraction! Certainly focused the mind of a low hour student!